Last week, Politico reported that the US Food and Drug Administration might wait until this summer to consider authorising a vaccine for children under five years old. Only a few days earlier, a judge had struck down the nationwide mask mandate on airplanes, prompting angry reactions from some who claimed that the ruling would result in dead children. Some parents have loudly proclaimed that they will continue to shield their kids from social interactions until a vaccine is available. And in New York City, children aged between two and four are still required to mask in schools because they are too young to be vaccinated.

As Covid restrictions and mandates have been dropped across the America and the Western world, unvaccinated kids have become a rallying cause for Americans unable or unwilling to leave the pandemic behind. But the truth is that children under five don’t need to wear masks and don’t need to have their lives put on hold pending vaccination. Hysteria about the risk to them is not just unhelpful but harmful. It deprives them of a normal childhood without any countervailing justification.

A decision on vaccines for young children is probably a few months away, given that U.S. public health authorities want to consider the Pfizer and Moderna vaccine data together. While some parents are understandably angry and frustrated with delay, the FDA is right to be cautious here. Young children are at low risk from the virus and the benefits of vaccinating them are uncertain. Even if the vaccines are approved, it is not clear that they will make a big enough difference to justify placing restrictions on children in the interim.

First, consider that the FDA has not tasked the vaccine makers with proving that their vaccine lowers rates of hospitalisation in kids. Nor do they have to show that the vaccines reduce MIS-C (an inflammatory condition that may arise after infection) or even rates of Covid infection. Rather, the FDA has asked Pfizer and Moderna to prove that their vaccines, at the dose given to kids, generate levels of antibodies that are comparable (or “non-inferior”) to levels of antibodies generated among older, fully vaccinated people. This is a low benchmark, and means that, in practice, the trials being run to clear it are very small. Indeed, they may be too small to detect reliable signals for the most important benefit — reduction in severe Covid — and for harms.

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Yet so far, Pfizer has failed to clear even this very low bar. Two doses of three micrograms of the Pfizer vaccine (1/10th the adult dose) fell short in December of 2020, to the disappointment of many. The FDA allowed the company to take another shot at it, literally, by adding a third dose. In late January of this year, there was buzz that the FDA would take the unprecedented step of authorising the vaccine despite the failed trial because it looked like it might reduce infections, but just a week later, Pfizer announced they would wait for the results of the 3rd dose before seeking approval. The flip-flop generated national news and outrage from some parents and doctors.

Then, on March 23, 2022, Moderna announced that its children’s vaccine — two doses of 25 micrograms, or 1/4 the adult dose — did generate sufficient antibody levels, again raising hopes that FDA approval would be forthcoming. But only limited results have been released so far. We don’t know the full spectrum of adverse effects, nor the impact on the outcomes we really care about: cases, severe disease, hospitalisations, MISC-C, and deaths. These outcomes are especially important for conducting a cost-benefit analysis for Moderna, which has clearly been linked to higher rates of myocarditis in young men than has the Pfizer vaccine.

As the clinical trials have dragged on, moreover, the landscape of kids and Covid has changed. Children have always been at relatively low risk, but newer variants appear to be even less risky for them. A recent preprint from the UK suggests that children infected with Omicron were less likely to be hospitalised with severe disease than children infected with the alpha or delta variants. We have also learned that MIS-C is less common often with the newer variants. Delta was less likely to trigger the condition than alpha, and CDC data suggests that omicron was less likely to trigger it than delta.

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More generally, it makes no sense to be overly cautious about low-risk children at a time when the United States is dropping most restrictions for adults. The risk to an unvaccinated healthy child under five is often lower than the risk to their vaccinated or even boosted parent. Natural immunity is also powerful and prevalent. It protects strongly against reinfection and even hospitalisation after reinfection. Not that the data here is from adults — naturally immune children are so rarely hospitalised that it is difficult to conduct studies on them.

Most kids have already had Covid, even if they and their parents don’t know it. Prior to the omicron wave, up to half of American children had been infected, and the virologist Trevor Bedford estimates that omicron might have since infected 40% of Americans. Although there is surely some overlap between the two numbers, most kids have probably already had Covid at least once, and it would be difficult for a vaccine to offer them any significant further protection. Finally, we have learned that vaccination has rapidly waning protection against symptomatic infection. Some studies report that vaccine effectiveness in those aged 5-11 for symptomatic Covid is less than 20%.

If you put all this together, the story becomes clear. The vaccine trials have been inconclusive. Most children have had Covid already, and the ability for a vaccine to further improve their health is limited. Finally, they are at extremely low risk to begin with. Parents may encourage their offspring to get vaccinated if and when vaccines become available, but they should not be consumed with fear pending FDA approval. Nor should they prevent their children from living a normal life.

This has largely been borne out across the world. For better or worse, countries such as Britain and France have been relatively united around their political leaders. Any perceived failures have largely been forgiven thanks to the sense that they were doing their best under difficult circumstances. There were even strange moments of forced unity: in the case of the UK, there was weekly applause for the NHS.

The only country in which this was not the case was the United States. From the start of the virus, the pandemic became as highly politicised as everything else. Aware that a roaring economy was one of the central pillars of his return to office, President Trump was unwilling from the start to respond drastically. He was, perhaps, the world’s most reluctant leader to concede to lockdowns or mask-wearing — and, as a consequence, both of these issues fell, like everything else, along entirely partisan lines.

Many who hated Trump became dedicated to mask-wearing precisely because the President was not. Single, double, or triple mask-wearing — even when engaged in an activity like jogging — suddenly became an even better way of displaying your political sympathies than wearing a “Biden-Harris” t-shirt.

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Likewise, the rejection of mask-wearing and an opposition to lockdowns became the mark of a Republican with a strong Trumpist sensibility. During a visit to the States ahead of the election I was struck by how New York, Los Angeles, Seattle and other Democrat cities were filled with mask-wearing lockdown enthusiasts. Towns in Florida, by contrast, resembled party destinations in an especially frenetic holiday-season.

There was a feeling throughout all this that the cause resided in the White House. Once Trump was gone, so the argument went, so the obscene divisiveness of American politics would recede and there might at least be some unified narrative on Covid and the national response to it.

Unsurprisingly, this did not happen. Trump may be long gone, but the polarisation of America’s pandemic politics remains. Vaccine hesitancy, in particular, has become an issue that divides the Left and Right. For example, one poll carried out last month found that while 86% of Democrats had received at least one Covid jab, while only 45% of Republicans had — and while a mere 6% of Democrats said that they would most likely avoid being vaccinated an extraordinary 47% of Republicans said the same.

It isn’t quite analogous to compare this situation with Labour and Conservative voters in the UK; this is clearly more than a political dispute. But even if you transpose the Democrat-Republican vaccine divide on to the most divisive British counterpart argument of recent years —Brexit — the divide is less pronounced. A poll carried out by YouGov in April found that vaccine hesitancy in the UK saw only a five-point difference between people who had voted Remain and those who had voted Leave.

There are a range of possible explanations for this. The first is that the UK’s Brexit divisions have begun to heal, if not completely. People who voted Remain have, by and large, accepted the new reality and do not in large numbers believe that they can continue to overturn the 2016 vote.

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In America, by contrast, more than half of Republican voters still believe that Trump won the last Presidential election and that the Democrats stole the vote. Around three in ten Republican voters believe that Trump will be reinstated as President this year. In other words, they believe the election was stolen, but that the facts are going to come out, forcing Biden to step aside.

And yet it is not only about politics. From the start of the pandemic, it was striking that reactions to the pandemic in America fell across a quasi-philosophical line. Most Americans have lived all their lives better acquainted with the concept of risk than their British and European counterparts. In part this is because of the absence of the European-style model of the welfare state. In Europe, life’s game of snakes and ladders exists in a much more sanitised form. But in the US, the reality is far more extreme.

The American Right’s suspicion of the state and state agencies remains more pronounced than it is on the European right. Ever since the British and European Right made their peace with the welfare state, there have been those who have wished to reduce the size of it, but no significant figure who has wished to abolish it. The same cannot be said for the US.

Ultimately, political polarisation has become a way of life, one that is more than capable of surviving the rotation of Presidents. Indeed, as a phenomenon I suspect it will only become more pronounced. At the end of last month, the CDC advised all Americans, including people who are fully vaccinated, to once again wear masks in a number of scenarios. And this week, more than a dozen large US corporations, including Walmart, Google and United Airlines, announced that their workers would be expected to demonstrate that they have had the vaccine in order to work for them.

So off the American cultural divide goes again. America may have survived the worst of the pandemic — but the deep divisions which it has highlighted look increasingly irreparable.

The Joint Committee on Vaccination and Immunisation (JCVI) explained that this is the result of a risk-benefit analysis. The JCVI’s Prof Adam Finn in a briefing with the Science Media Centre pointed out that “happily the virus very rarely affects children seriously”, and that the very small risks of adverse effects from the vaccine outweigh the risk to a child of getting, and then becoming ill with, Covid. The UK medicines regulator has declared the Pfizer vaccine safe and effective in children, but the JCVI has a more stringent approach.

Similar calculations were made back in March. At the time, a small number of cases of a rare clotting disease were detected in people who had had the Oxford/AstraZeneca vaccine. As a result, the JCVI recommended that it not be used in the under-40s unless no other options were available.

That decision was based on a straightforward risk-benefit analysis. The risk of a blood clot caused by the vaccine is vanishingly small – about one in 50,000, with the risk of severe health impacts lower still. But young people are also at very low risk of getting severely ill if they develop Covid, and the number of people with Covid at the time was very low – only about 6,000 new cases a day, compared to about 60,000 at the January peak. That meant that the chance of a young person getting infected, and then getting very ill, was even smaller than the risk of a blood clot, as the Winton Centre for Risk and Evidence Communication showed.

“Freedom Day” has happened now. It’s far from clear what effect it will actually have. The Government’s Scientific Pandemic Influenza Group on Modelling (SPI-M-O)’s latest modelling paper, published last week, says that by the end of August, we could end up with fewer than 100 hospitalisations a day, or more than 10,000. 

Small changes to our assumptions drive huge changes to the outcomes: will 90% of people stop wearing masks? 70% 50%? Will we all pile into nightclubs and theatres, or only a few of us? We don’t know: these things, or a million others. As the Bristol maths professor Oliver Johnson puts it, “the range of uncertainty around any reasonable forecast probably includes both ‘it’s basically fine’ and ‘we have a very serious problem’.” 

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What we do know, though, is that cases were already growing before Freedom Day. The R value is well above one. If we wanted to reduce the number of cases, to make the line on that chart actually go down, then we would need to reintroduce some (probably quite stringent) measures. That seems unlikely.

But what we can do is get more people vaccinated. And it seems that two obvious ways of doing that are to vaccinate children, and to start using the Oxford/AstraZeneca vaccine in younger people again.

Vaccination makes a huge difference to Covid risk, in every way. Which is why it’s a problem that our programme has tailed off so much. On one glorious day back in March, 844,000 vaccine doses were reported to have been administered across the UK. That was anomalous; but from March until about June, there was an average of between 500,000 and 600,000 doses being administered every day.

Since early June, though, those numbers have sagged dispiritingly. It’s been more like 250,000 for the last few weeks.

So how do we get it back up to higher levels, given that vaccine coverage is more important than ever? 

There are two drivers of vaccine uptake: supply and demand. The most obvious problem, at the moment, is that demand is down. Paul Mainwood, a strategist who has spent recent months looking at vaccine delivery, points out that first-dose vaccine uptake shows a distinct curve. At first, each age group is vaccinated slowly, so the numbers creep up; then it accelerates, and shoots upward; then, as it nears 100%, it levels off again. The curve on the graph is S-shaped..

With the over-50 age groups, that flattening-off happened at above 95% coverage; but as you come down the cohorts, the levelling-off happens earlier and earlier. For 30- to 34-year-olds, the line has flattened significantly and it hasn’t yet reached 80%. For 18- to 24-year-olds, it’s lower still: the flattening is visible and it’s only around 65%.

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That suggests that there is reluctance among younger people to get the vaccine. Whether that’s true anti-vaxx attitudes, or an understandable wariness of feeling rubbish for a day or two in exchange for a reduction in an already tiny risk of death – or an equally understandable, if in my view wrongheaded, concern about the more severe side-effects – is hard to know, although the ONS says that “vaccine hesitancy” is rare. Even among 16- to 29-year-olds, the most hesitant group, only 13% say they are reluctant to take the vaccine. But even if they’re not reluctant, we seem to be running out of people who are noticeably keen.

How you persuade those increasingly hard-to-reach groups is disputed. Finn of the JCVI said that one reason they were being so stringent is that they are worried about “the impact on public trust” if the JCVI recommends vaccines for groups who would not directly benefit from them: I worry about the opposite problem, about the impact on public trust if you tell the public that the vaccines aren’t safe. 

But given that demand is a problem, it does seem that an obvious way to increase demand would be to widen the availability of the vaccine. About 20% of the UK’s population is under 18; roughly 13 million people. Probably about four million of those are between 12 and 18. We can expand demand simply enough by offering it to them.

One question is, of course, whether we could vaccinate those young people quickly enough to make a difference. 

It does seem that the UK is not, right now, struggling with supply. I spoke to Kevin McConway, emeritus professor of statistics at the Open University, and he noted that all his local vaccine centres have walk-in availability for Pfizer, suggesting that it’s not an immediate problem.

But Mainwood estimates that we are bumping right up against our supply with Pfizer. If we were to take steps to speed up vaccination – by offering second doses earlier than eight weeks, for instance, or by allowing teenagers to be vaccinated – we would struggle.

The thing is, though, we have literally millions of AstraZeneca vaccines sitting unused. We bought 100 million. It’s very hard to get detailed breakdowns of which vaccines have been used, something that Professor Sir David Spiegelhalter, who I spoke to, is somewhat annoyed by: but we can’t have used more than 82 million AZ doses, since that’s the total number of vaccine doses administered. Probably it’s more like half that. 

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And since those March days when the AZ risk-benefit calculations were carried out, the situation has changed enormously. Now, the number of cases every day is back up around 50,000, not far off the January peak. The latest ONS infection survey finds that around one person in every 95 has the disease right now. And it’s highest among the youngest age groups – almost 3% of 17- to 24-year-olds have it. The Winton Centre’s analysis suggests that when the numbers are that high, the risk-benefit analysis changes utterly. A twentysomething has about a one in 50,000 chance of a blood clot if they get the AZ vaccine ,but a higher than one in 16,000 chance of going into intensive care with Covid in the next 16 weeks if they don’t.

If we freed up those AZ doses, we could do all sorts of things. For one thing, we could offer people a mix-and-match vaccine dose, so that people who want their booster earlier than eight weeks could do so. The evidence of effectiveness for mixed Covid jabs is now quite good, and it may even be more effective than two jabs of the same dose.

And we could offer vaccines to older teenagers who are willing, with their parents’ consent, to take a very low risk of vaccine side-effects in exchange for a significantly decreased risk of spreading the disease.

People should be able to make these decisions, or in the case of older children, to make them in concert with their parents, just as we allow them to make other decisions about risk and wellness. Perhaps they would need to sign a waiver; but they should be allowed to.

In about seven weeks, children will be going back to school after their summer holidays. The virus will, in all likelihood, still be circulating at least as much as it is now. We will head into winter with few restrictions, possibly with new variants, and still, probably, with a large percentage of the population unvaccinated. We could significantly reduce that percentage if we allow people to make their own decisions about what is important.

Now that Freedom Day is here, we ought to allow people a real freedom: the freedom to choose to be vaccinated.

The outrage was the subsequent blame-shifting manoeuvre by the European Commission. While the accusation that AstraZeneca was diverting vaccine supplies from the EU to the UK was absurd, the consequent threat to impose a hard border on the island of Ireland was shockingly irresponsible. Widespread condemnation forced the Commission to back down.

The scandal is what happened next. For a start, and despite the fiasco and the outrage, no one has resigned — least of all Ursula von der Leyen, whose cool-and-calm exterior conceals a heart of beating ineptitude.

Then came a spectacular display of sour grapes. After all the fuss about not getting enough of the Oxford AZ vaccine, various EU powers-that-be have undermined its reputation.

It all kicked off with a report in Handelsblatt on the 25 January. The piece featured a claim — from a mysterious source within the German government — that the vaccine was only 8% efficient among the over-65s. Unsurprisingly, this made headlines around the world.

Could this possibly be true? No, said AstraZeneca, the figure had no basis in their research or anyone else’s. So where did it come from? An investigation for the BMJ by Hristio Boytchev tried to get to bottom of the matter, but all we can say for sure is that an unnamed source in the German health ministry was very keen to get the fake news out there.

In any case, the murkiness soon became manifest. Within days of the anonymous briefing, the German and French governments announced that they would not be allowing the use of the vaccine among the over-65s.

In comments to the press on the 29 January, Emmanuel Macron made it clear what the French attitude would be: “everything points to thinking it is quasi-ineffective on people older than 65, some say those 60 years or older.”

But “everything” did not point to that conclusion. The British had already approved the vaccine (on the 30 December) and had been successfully using it since. On the same day as Macron’s remarks to the press, the European Medicine Agency (EMA) also approved the use of the vaccine — among all adult age groups. Furthermore, they specifically addressed the issue of older age groups:

“There are not yet enough results in older participants (over 55 years old) to provide a figure for how well the vaccine will work in this group. However, protection is expected, given that an immune response is seen in this age group and based on experience with other vaccines…”

As Tom Chivers explained for UnHerd here, it’s entirely reasonable to expect encouraging results from trials conducted mostly on younger age groups to hold true for their seniors, too. And yet the President of France saw fit to state that “the real problem on AstraZeneca is that it doesn’t work the way we were expecting it to.”

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If anything, the vaccine has exceeded expectations. Results from England show that inoculation has cut the risk of serious illness in the over-80s by around 80% — building on similarly impressive results from Scotland. That Handelsblatt claim wasn’t just wrong, but wrong by an order of magnitude.

Note, also, that these results are for a single shot of the vaccine. The second shot should produce even better outcomes. Nevertheless, the degree of protection already achieved has triumphantly vindicated the decision to spread out the shots in order to vaccinate as many vulnerable people as possible. More reason, then, for Macron to eat his words — because as well as pouring doubt on the efficacy of the virus, he poured scorn on the UK’s first shot first strategy, stating: “I’m not sure that it’s very serious.”

Well, it is serious, as are the consequences of the EU’s sour grapes. The irony of the supply dispute with AstraZeneca is that shots of the vaccine are now going unused in the EU, because intended recipients (like the older under-65s and health workers) are worried there might be something wrong with it. In Germany, regional governments are pleading with Berlin for permission to reassign doses to people in lower priority groups who are willing to take it.

The contrast with the British experience becomes more embarrassing by the day. Though one would expect Covid deaths to fall as a result of the UK strict lockdown, they’ve been tumbling fastest among the most extensively inoculated age groups — compelling evidence that our vaccine strategy is working.

The Europe Union is now waking up to what it needlessly missed out on. Worried EU governments are now desperately reassuring their populations that the Oxford AZ vaccine is safe and effective. The French have just relaxed the restriction on the vaccine’s use among the over 65s. The Germans are likely to follow suit. Thomas Mertens, head of Germany’s  expert panel on vaccine use, has promised an “update” to the current regulations. He was at pains to point out that the existing restriction were never about safety concerns and added that “somehow the whole thing went kind of badly wrong.” Yeah, “somehow”.

In the latest blow to European solidarity, Denmark and Austria have chosen to go their own way, obtaining vaccines via Israel; Slovakia has joined Hungary in acquiring the Russia Sputnik vaccine, believed to be safe although yet to be approved by Brussels; while Poland is considering a deal with China.

And yet the EU’s leaders continue to send the wrong signals. Last week, Angela Merkel said that she would not take the Oxford AZ vaccine herself. Her British defenders point out that this is only because she is 66 and thus just above the age at which the current restrictions kick-in. But, as usual, her apologists miss the point. The rules — which she is ultimately responsible for — are ridiculous and should not exist in the first place. As leader of her country, millions of people will follow her lead.

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Of course, hers is not the only screw-up in this pandemic. There isn’t a country in the world that hasn’t got it wrong repeatedly — and the UK is clearly no exception. However, it’s important that we distinguish between the different kinds of mistake.

About a year ago, Britain should have gone into lockdown at least two weeks before it actually did. However, our Government was acting on official scientific advice that was unfortunately wrong. Other failures arise out of the sheer scale of the challenge, test-and-trace being a prime example. We can test at scale, but tracing is supremely difficult when transmission is so widespread. It might have helped if we’d closed our borders at the outset — but that’s an illustration of a third kind of mistake, those that happen when governments are faced with impossible dilemmas. Choosing the lesser of two evils isn’t easy when they’re both overwhelmingly horrible.

The mistakes made by Brussels, Paris and Berlin over recent weeks have been of a different type, and were entirely avoidable. In deciding policy towards AstraZeneca and its vaccine, the scientific advice (from the EMA) wasn’t wrong, the challenges weren’t insurmountable and the choices far from impossible. There was no question as to the safety of the vaccine. There was a degree of uncertainty as to its effectiveness, but good reason to expect a beneficial outcome. After all, for millions of elderly and vulnerable Europeans the alternative isn’t a better vaccine, but no vaccine — a famously ineffective treatment.

The mistake made in this matter was not an honest one. There’s only one motivation that fits with the facts — spite.

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As an institution, the EU displays a pattern of behaviour that in an individual would be diagnosed as petty narcissism. We all know the type of person: the character flaw isn’t obvious at first, but they soon give themselves away. In place of the usual give-and-take of a healthy human relationship, they think they’re doing you a favour just by allowing you to interact with them. Furthermore, you will be expected to pay for the privilege. This means abiding by their rules; having to guess what they want without being told; prioritising your relationship with them above any other attachment. Resist their nonsense and you’ll be accused of being the unreasonable one.

If an impasse is reached or you walk away, they won’t wish you well. Indeed, like Jean-Claude Juncker insisting that “Brexit cannot be a success”, they’ll want to you fail without them. And, of course, that’ll be your fault, not theirs. It’s abusive and manipulating, but ultimately self-destructive.

Instead of bullying and then belittling AstraZeneca and the UK, the EU could have chosen the path of cooperation. Even if they genuinely did have questions about the vaccine and the UK’s vaccination strategy they could have kept an open mind — and thus the option to follow suit. As it is, they’ve ensured that any change of mind can only come with a maximum of political embarrassment and humiliation.

Well, never mind — let them pay with their blushes. After all, their people are paying with their lives.

The natural extension of all of this euphoria has become the need to prove that you’ve been immunised. And so the concept of the “vaccine passport” has been born; a digital document or smart phone app, a magic ticket that will allow you to hop on a plane, go to the theatre or pop to the pub.

Only last week, after facing pressure from countries reliant on summer tourism – including Greece, Italy and Spain — European leaders confirmed their intention to create an EU-wide vaccine certification scheme that would record people who had received approved jabs. “Everyone agreed that we need a digital vaccination certificate,” Angela Merkel, the German chancellor, said after a virtual summit. “This will make travelling within the EU possible and could pave the way for further travel from third countries into the EU.”

It’s hardly surprising, then, that an array of British start-up companies is now jostling to produce a bewildering collection of “travel passes”, “immunity certificates” and “health passports”. But what, exactly, are they? And how will they work?

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First, it is important to remember that proof-of-vaccination documents are nothing new. Seasoned travellers have long been required to have certain inoculations before being granted access to some countries. These have, however, never existed in the context of a pandemic; so, in the past, if you had not had a jab against yellow fever, then you would have been barred from only a handful of countries — if you haven’t had a Covid vaccination, the effect on your travel plans could be much more profound.

The vaccination passports currently being mooted are broadly divided into two types: those intended for international travel and those you might be required to show if you wanted to access an office or entertainment venue — though the best solution (if, indeed, you regard such passports as a “solution” at all) would be for a vaccine passport to be recognised both by national border officials and pub bouncers.

Whatever their purpose, all these documents and passports do have one thing in common: they provide verification of a person’s identity — usually through biometrics or facial recognition — as well as up-to-date access to medical records showing their vaccinations, boosters and so on. Some also record whether a person is positive for antibodies, indicating that they have already had Covid-19.

In the UK, it’s worth noting that this path was not always inevitable. In fact, a succession of ministers initially said vaccine passports were not being considered by the government. But, with the prospect of lockdown being lifted now on the horizon, they have rowed back in the past couple of weeks. Indeed, in spite of the government’s initial reticence, almost half a million pounds in grants had already been awarded to eight companies working on variations of vaccine passports before Johnson’s “roadmap” was announced.

Among them is Logifect, a “global digital health solutions provider” which has received £37,000 to help develop a smartphone app to confirm immunity. Before the pandemic, Logifect was already involved in what it described as “the next generation of digital health”, which would enable individuals to access their medical records, receive healthcare advice and manage medical devices from their smartphones.

Its immunity passport, says Commercial Director Sean Power, would be a spin-off of that. First you would download its app to your smartphone. Using your camera within the app, you would be asked for a scan of your passport or driving licence, and then to have your picture taken for comparison and verification. Then, when you needed to demonstrate that your vaccines were up to date, you would open the app and give permission for your vaccine record to be accessed and for a QR code to be produced. This could then be read by the checker’s smart device, which would display a message with your photo confirming your vaccine status.

“Your picture links you to that record — your name doesn’t even appear,” says Power. “The communication is fully encrypted at both ends for complete security and then everything is deleted in seconds.

“We see this as a way of making a positive contribution to the community, with our costs being covered by a small fee — probably pennies — to the venue or authority that requests the information. It would cost the user nothing.”

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Meanwhile, iProov, a biometrics ID company that lists the US Department of Homeland Security and the UK Home Office as clients, and cybersecurity firm Mvine, which has already worked on projects with the Cabinet Office and NHS, have been given a joint £75,000 grant to develop an app that would perform a similar task to Logifect’s.

iProov’s founder and CEO Andrew Bud tells me their system involves the creation of a certificate to demonstrate that you have been vaccinated. They have developed a number of options, some of which will need the involvement of the Department of Health.

Currently, vaccination records are held by the National Immunisation Management System, which is run by Public Health England, Scotland and Wales independently of the NHS, and within GP surgery patient records. The iProov/Mvine system proposes storing these vaccination records using cloud technology, so they are neither held on your phone nor within existing NHS record systems.

“One of the defining features of the Mvine/iProov system is that it is designed for privacy,” says Bud. “It doesn’t require a name or address or date of birth or National Insurance number or any other irrelevant data. Our system is designed to associate the existence of a valid vaccine certificate with a face.”

Other companies that have received grants include: EAS Technologies (£137,877), which is focusing on vaccine verification for sporting events; the Hub Company (£49,448), which features PayPal and IBM among its clients; Enduring Net (£49,678), which says it usually focuses on technology “in humanitarian work”; and Verifiable Credentials (£89,000), which is planning to create “Covid-19 certificates” that cannot be forged.

But they are not only runners in this race. In fact, the UK Government is undertaking a three-month review of “vaccine passport” technology and may even consider repurposing the pre-existing NHS app — separate to its track and trace app — which gives people access to their medical records.

However, according to Phil Booth, co-ordinator of medConfidential, a campaign group promoting best practice in safeguarding the confidentiality of medical records, this would likely be unpopular among NHS staff.

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“It would essentially turn the NHS into a clearing house for information requested by the private sector,” he says. “This would find great resistance among those responsible for NHS Login [the online portal that patients can use to access a host of services and see their GP medical records]. Being forced to be a certification authority in the midst of all their other pandemic work would be a massive drain on resources and, frankly, a distraction.”

Moreover, Booth says, it is unclear what the purpose of all this technology would be: “It would be impossible for the government to partner up with private companies to produce vaccine passports until everybody had had the offer of a vaccine — otherwise requiring a passport to get through everyday life would be discriminatory.

“But the vaccine take up is so great — about 90 per cent in the higher age groups — that by the time everybody has been offered one, we will probably have reached herd immunity. So, what’s the point of having a passport that will get you into a pub in those circumstances?”

Still, that hasn’t deterred countries across the world from investing in this technology. Israel was one of the first, followed by Greece, Malta, Portugal, Israel, Estonia, Sweden and Norway. None of these countries has said that foreign internationals without proof of vaccination would be refused entry, but instead would be subject to other — more laborious and time-consuming — testing or quarantine regimes.

Domestically, Israel is the only country to have vaccinated enough people to have a system that is already functioning. About half of its 9.3 million citizens have received the two jabs required to qualify for a “green pass” that they can display using a Health Ministry app on their phones — people with such passes are already being granted access to restaurants, shops and theatres.

Airlines, too, are getting in on the act, courtesy of the pre-existing International Air Transport Association (IATA) Travel Pass app. This provides information to travellers on the Covid requirements of the country they are travelling to, tells them where they can get tested if required, enables labs to send results directly to passengers, and, crucially, provides for the creation of a digital vaccination record once governments make them available.

Among those already trialling aspects of it are Singapore Airlines, Etihad, RwandAir, Emirates, Qatar Airways, and Air New Zealand. Moreover, on top of all these initiatives is a whole host of private sector travel and vaccination record schemes, among them IBM’s Digital Health Pass, Daon’s Verifly (currently being trialled by BA and American Airlines) and Microsoft’s Vaccination Credential Initiative.

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But with the creation of so many disparate apps and vaccination confirmation systems, surely we will need some kind of international co-ordination for them to be practicable. And there is currently only one body that has an internationally-recognised proof-of-vaccination scheme — the World Health Organisation’s Yellow Card. Indeed, it increasingly seems that the WHO will be called upon to provide a solution to all this apparent chaos.

Already it has teamed up with Estonia — arguably the country with the world’s most efficient joined-up governmental IT architecture — to come up with a system that would enable national “vaccine passport” solutions to work in an international setting.

At the forefront of this partnership is Marten Kaevats, National Digital Adviser to the Estonian government and a member of the WHO’s Digital Health Technical Advisory Group. He says no new technology would be needed for an international system to work. Instead, building up trust among nations, so that they can rely on the information provided by others, would be paramount.

“We currently see most of the different governments deploying various sorts of their own technologies,” he tells me. “In order for these technologies to be able to co-operate with each other, we need to agree upon common global standards and principles.”

The WHO has set up a Smart Vaccination Certificate Working Group in order to achieve this. But, says Kaveats, “the WHO doesn’t currently have a mandate to become the global anchor of trust for cross-border health data services. It could be given that at the end of May when the World Health Assembly [the decision-making body of the WHO] next convenes.”

With the threat of other Coronavirus variants — or entirely new viruses and pandemics — continuing to loom over us, it certainly seems only a matter before an international solution such as the WHO’s is devised. In the meantime, the race for a vaccine may be over. But the race to create vaccine passports has only just begun.

The big response, of course, is vaccines. All the rest of it, all the rapid testing, track and trace stuff, can help control the virus with fewer restrictions on our daily lives. Only vaccines hold out the realistic possibility of getting rid of it altogether, and (eventually) returning to normal.

So it is potentially extremely good news that Pfizer-BioNTech have announced that early results from their trial show that their vaccine candidate, an mRNA vaccine, is around 90% effective. How close, then, is that return to normal?

Boris Johnson says that we have awaited “the distant bugle of the scientific cavalry coming over the brow of the hill” and that now “that toot of the bugle is louder”, but that it is still some way off. The turn of phrase may be tooth-grindingly irritating, but he is basically right.

In short: this is very exciting; the vaccine almost certainly works, although it would be nice to have a bit more clarity about what “works” means; and it’s worth remembering that, beyond just proving that it works, producing it in large quantities and getting it to where it’s needed are real challenges as well. But, mainly, it is completely okay to be excited, as long as you realise that it’s still a few months to wait. 

I think, though, we can be pretty confident that the vaccine actually works. It would be understandable to be sceptical because there has, as yet, been no scientific paper released, or even very much data, beyond one simple number: 94. 

That figure is the total number of cases in both arms of the trial. There were 43,538 people on the trial; according to the study protocol, half of them were given the real vaccine, and half a placebo. Three weeks later, all but 4,000 or so received a booster shot, of the same jab (either the vaccine or the placebo) they had before.

According to the Pfizer press release, there were 94 cases in total, and “the case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90%”.

What that means is that the vaccine prevented at least 90% of cases, so there were 10 times as many in the placebo group as the real vaccine group. Say there were 100 cases in the placebo group and 50 in the other: that would mean that it was 50% effective; if there were 100 in the placebo and ten in the real vaccine group, that would mean it was 90% effective.

In this case, if there are 94 cases in total, there can’t have been more than eight cases in the real-vaccine group, and 86 in the placebo group, for it to be “above 90% effective”. And we also know that the vaccine is astonishingly safe, given no major adverse events in the 20,000 people who were given it.

Again, we have no further data, and it’s always sensible to be wary when ‘pharma company puts out press release saying pharma company’s product is great’. But the results weren’t released by Pfizer — they were put out by an independent monitor, the Data and Safety Monitoring Board (DSMB), so it would be pretty astonishing if they have just made this up.

What might seem more worth worrying about is whether this could be a fluke result. This isn’t, after all, the final analysis, and if you release data from a trial before it’s finished, it’s reasonable to be worried that it’s wrong. 

Let me explain, with this excellent analogy from Tim Harford’s new book How to Make the World Add Up. Imagine that two basketball teams are playing a game, and you want to determine which team is the best. You could just say “whoever wins is best” but it might just be a fluke. So you say beforehand: let’s draw an arbitrary line. If one team wins by a given number of points — let’s say 20 — we’ll say they’re the best. Otherwise we’ll say the results are “not statistically significant”. The higher that number, the more certain you can be when someone does reach it, but also the more times you’ll have to say “we don’t know” because they don’t.

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That’s pretty much how scientific studies work. They say: “If the vaccine does better than the placebo, that could be fluke. So we’ll draw an arbitrary line and say if it does this much better, then it works well enough and we’ll use it.” The arbitrary line was 50% — so if there were 50% fewer cases in the real arm than in the placebo, they’d say it worked well enough.

But if, in the basketball game, one team was 20 points ahead in the second quarter, and then that team’s manager said: “Okay, let’s end the game there”, you wouldn’t think that was a fair assessment. Showing results from the trial early could be doing the same as that.

However, that’s not quite what has gone on here. The plan was always to release data after 32 cases were detected, then again after 62 and 92. (See Table 5.) For reasons that they don’t make clear, but which were “after discussion with the FDA”, Pfizer decided not to release its findings after 32 cases; by the time those discussions were complete, they’d already reached 94 cases. The study will continue until they reach 164 cases, but releasing early data was always part of the plan — so I don’t think it being released now should undermine our confidence at all. 

The other possibility would be that this result is a freak of some kind, that more people happened to get the virus in the placebo group than in the vaccine group. But that’s probably not a serious concern, and we can pretty much rule out the possibility that the vaccine does nothing. If it did, then seeing an 86-8 split would be as unlikely as tossing at least 86 heads in 94 coin-tosses, which is so unlikely that it’s essentially impossible. A one-in-some-number-of-quadrillions chance. 

The real number could be slightly more or slightly less than 90%, but realistically, not very much more. We’re talking no worse than 80%, at the outside. So I think it’s fair to say that the vaccine probably works, and is very effective. The next question is: what exactly does it do?

That might sound stupid — it stops Covid, of course. But what’s not completely clear to me is whether it stops Covid from infecting you or it stops Covid from making you ill. 

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In the trial I’m on, of the Oxford-AstraZeneca vaccine, I have to do a nasal and throat swab every week to see if I have the virus. So it’s very unlikely that I’d get infected and not know about it.

That’s not what happens in the Pfizer-BioNTech one. They seem to only swab people when they come in for follow-up appointments every few weeks or months, or when people get symptoms.

Robin Shattock, who runs Imperial College London’s own vaccine programme, describes it as “a symptom-directed endpoint that requires virological confirmation”. Nilay Shah, a professor of chemical engineering at Imperial, agreed: “My understanding is that the 94 cases must be both symptomatic and RNA-positive to be counted.”

What that could mean is that lots of people in the vaccine group are becoming infected — as in, some detectable amount of virus has entered their bodies and started replicating — but that they are not getting ill, so they’re not getting tested. Shattock told me that even people with mild symptoms, “runny nose, headache, fatigue etc”, would be tested, but still, it could easily miss some infected people.

Obviously it would be better if people were definitely being protected against infection as well as disease, since asymptomatic people can spread the virus. But even if the vaccine has literally no impact on infection rates at all, stopping 90% of symptoms is a big deal. What’s more, asymptomatic people probably spread the disease much less, and besides, it’s very unlikely that the vaccine will have no effect on infection. 

I spoke briefly to Vishal Gulati, a biotech investor and former virologist, and he said that even if the vaccine only protects against disease, it would be “nice to have”, but that he thinks it’s amazingly unlikely that it doesn’t have an effect on the viral load itself. “It’s just not possible that someone who is not sick is producing the same amount of virus over a significant period as someone who’s getting sick,” he said.

It may be that the vaccine is a really good one to give to older and more vulnerable people, to keep them safe, and that later vaccines that are more effective against infection should be given to younger people to stop the spread. According to the protocol, the study is doing antibody tests, so hopefully when the full data is released we’ll know more about the impact on infection as well as disease.

So it probably works well, and most likely reduces the effects of the disease as well as infection. The next problem is going to be making enough of it.

RNA vaccines like the Pfizer one, although completely untried, do have some big advantages. 

One is that making RNA is quite easy. If you have the ingredients – a big soup of nucleotide bases – you can get your length of RNA that you want, and it will essentially replicate itself. You can do it with relatively low-tech materials and at small scale, and each time you need a new length of RNA (for a different vaccine, perhaps), you can reuse the same facilities. Also, the doses are quite small, so you can make more doses per litre in your bioreactor. 

But you still need a lot of doses. Let’s be optimistic and say that it does protect against infection, and that you need to vaccinate 60% of the population to get herd immunity. (For a discussion of what “herd immunity” is, see here, but essentially, it’s the percentage of the population you need to vaccinate to get the R below 1. So if the R is 2, you need to vaccinate 50% of the population, so it’s twice as difficult for the virus to spread.)

In the UK, you’d need to vaccinate about 42 million people. But we’d need two doses per person, so that’s 84 million doses. And, remember, the vaccine is probably only around 90% effective, so about 10% of them won’t work. You’ll end up needing about 94 million doses to vaccinate the whole country to a herd immunity level. If we actually need 70% coverage, then that number is 110 million.

The UK government has ordered 40 million doses from Pfizer. That’s a big deal – it should be enough to vaccinate about 18 million people successfully. If we concentrated that on healthcare workers and the most vulnerable, then it would significantly reduce the number of deaths. But it won’t stop the spread of the disease itself. 

Of course, when the AstraZeneca vaccine is licensed, we’ll end up with another 30 million in short order and 100 million eventually. So UK herd immunity will probably happen. But even so, it is only a temporary reprieve if the virus is still endemic in the rest of the world. To immunise the entire world to herd immunity levels, you’d need about 10.5 billion doses.

Pfizer thinks it can make about 1.3 billion doses next year. Moderna, who are making another RNA vaccine, say a similar sort of figure. But what’s not clear is whether those two estimates take into account the fact that both companies will need the same raw materials; if both companies are ringing the same suppliers and trying to buy all their nucleotides, then one of them is going to be disappointed. I go into a bit more detail about the problems here.

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This is why we simply cannot make do with just the Pfizer vaccine. The Oxford one, for instance, is a viral vector vaccine, and won’t need quite the same chemical components as the Moderna and Pfizer ones, so their supply chains won’t interfere with each other so much.

There’s another problem which is that RNA vaccines such as Pfizer’s need to be kept at -80°C for all but the last day or so before they’re administered; Moderna’s needs -20°C. Other types of vaccine just need to be kept at normal fridge temperature, between 2°C and 8°C. This isn’t an insurmountable difficulty, especially in the UK, but it does mean that you couldn’t, say, bring a batch to a GP’s surgery on Friday and administer it on Monday, unless the surgery had a really high-tech freezer.

In the developing world, that will be an even greater challenge, but it is worth noting that the novel Ebola vaccine developed during the 2014-15 outbreak required a -60°C cold chain, and it was rolled out rapidly to hundreds of thousands of people in the middle of a war zone. These cold chains can be established fast.

There’s one more thing that’s worth mentioning. Donald Trump Jr, among others, is floating the possibility that the vaccine announcement has been delayed in order to help Joe Biden get elected. And you might be tempted to believe him – remember that, earlier on, we mentioned that Pfizer were going to release some preliminary results after 32 cases, and again after 62. But they didn’t end up releasing anything until they’d reached 94 – which, as it happened, was just a few days after Donald Trump Sr had lost the US election.

You can understand people’s suspicions. But it’s worth noting that Pfizer couldn’t have known that the results were positive, because they wouldn’t have had access to them. The only people to have access to the unblinded data – that is, the only people who knew which test subjects had the real vaccine and which the placebo – was the DSMB, the independent body supervising the study. And it’s not Pfizer or BioNTech who decided to release the data: it’s the DSMB.

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It’s not that it’s impossible that this panel of independent scientists were conspiring to help Joe Biden win the election, it just seems unlikely. Gulati thinks the most likely explanation is simply that the DSMB decided that releasing the data early, when the statistical power was still very low, would have reduced public trust in the vaccine. Also, it might have made recruitment for the trial more complicated, if it was obvious that the vaccine outperformed placebo — telling people there’s a 50% chance they’ll be in the placebo arm would not be hugely popular.

To sum up, then: this is a really big deal. It looks like the first vaccine will arrive soon, and that it will work – much better than expected, although with slight question marks over how well it “works” on infection as well as symptoms. And it’s really reassuring that vaccines work at all.

What it doesn’t mean is that we’ll all have the vaccine tomorrow, or even this year, or perhaps even next year. And it certainly doesn’t mean we can stop developing and producing the other vaccines, because each kind of vaccine will have different strengths and weaknesses — some will be easier to manufacture, some will work better in different groups. (There’s a useful Twitter thread on this topic from the CEO of the biotech company GreenLight.)

The best-guess timeline, that most people will probably not see a vaccine until late next year, is still reasonable. And, of course, it would be really nice to see the data from this Pfizer study, rather than just a few bullet-points and self-satisfied quotes in a press release.

Nonetheless, it’s exciting. It’s a light at the end of the tunnel. And finally, it gives a nice straightforward answer to what it is that lockdown is supposed to be buying time for.

Back in March, pundits and experts were not hopeful: some were confident that it would take over 18 months, some thought at least two years, and others predicted several years. Five months on, with over 165 vaccines in development, Dr Anthony Fauci, the American epidemiologist advisor to the White House, says that an effective vaccine will be available in the US early or midway next year. And superforecasters – the paid experts whose job it is to successfully predict events – tend to agree.

Are we really on the verge of achieving something that was previously inconceivable: a vaccine for an entirely new disease, developed within a year? And who can make that prediction? On the one hand, there are scientists, who have deep knowledge of viruses, infectious disease, immunology, epidemiology and biology — but they may be unfamiliar with the global economic and political events that could influence vaccine development in a time of crisis.

On the other, there are superforecasters, who have broad knowledge of global issues, and skills and experience in their approach to making forecasts — but they may be unaware of certain quirks of viruses or the immune system that influence how difficult or easy it may be to develop an effective vaccine.

When estimating a vaccine date, the best approach might be to combine the knowledge and skills of both groups. But before that, we need to define the question we want to answer precisely. Do we want to know how long it will be until a Covid-19 vaccine is approved (for anyone? for the general public?). What about the vaccines that have been authorised in other countries, such as China and Russia? Perhaps we want to know how long it will be until there are a certain number of doses of vaccines that have been approved in the US and the UK? All of these questions might be interesting, but for the purposes of this piece, the last one may be most relevant.

At this point, it’s important to find an accurate ballpark estimate to work from, and it’s easy to be swayed by the predictions of other experts and media reports. As Philip Tetlock and Dan Gardner explain in their book Superforecasting: “When we make estimates, we tend to start with some number and adjust. The number we start with is called the anchor. It is important because we typically underadjust, which means a bad anchor can easily produce a bad estimate.” This effect, called anchoring bias, has been demonstrated in many large experiments.

Vaccines normally take a long time to develop, usually between 12-15 years from research to trials to approval and to distribution, and at each stage, the probability that any given vaccine candidate will make it through drops until only a few candidates, if any, actually succeed.

But today things are moving faster than ever before. This is partly because of improvements in biotechnology (such as cheaper genome-sequencing), computational speed, open data sharing, and preprints. But more significantly, the gravity and urgency of the situation have put the pandemic at the centre of attention, and there is more money for Covid-19 vaccines than for any previous types.

On top of this, scientists already have research from other similar coronaviruses (MERS and SARS), and some pharmaceutical companies already work with animal models of the disease and have factories to produce vaccines for their trials. What’s more, researchers don’t have to go through each phase of trials one-by-one, as they would usually, but can start multiple phases simultaneously to speed up the process.

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Some pharmaceutical companies have even started manufacturing some vaccines at scale so that they can be distributed swiftly, anticipating that they might be approved. The approval process, during which regulators scrutinise the evidence and inspect factories to find out how safe and effective a vaccine actually is, typically takes an additional year, but regulators have said this will be fast-tracked and begin while trials are ongoing. This means that a timeline that would usually take 12 years could be accelerated to 18 months or less.

And some previous global pandemics offer hope. In the spring of 1957, an American microbiologist called Maurice Hilleman, after reading a story in the newspaper, concluded that a deadly influenza epidemic in Asia could become a global pandemic. He sought out samples of the virus, and found it was a strain that most Americans had not encountered before, and therefore had no immunity to. Hilleman worked personally with vaccine manufacturers to scale up production, so successfully that the vaccine was trialed in patients in July that year; by the autumn, factories were ready with 40 million doses. This whirlwind speed massively reduced the impact of the Asian flu pandemic in the US and abroad – a timeline of only 4 or 5 months.

With other pandemics, though, we have not been so fortunate. During the Spanish flu of 1918, researchers were unable to identify the pathogen that caused the disease, while doctors often misdiagnosed patients, all of which interfered with the development of a vaccine. More recently, the HIV pandemic remains without an effective vaccine, decades since the virus was discovered.

Clearly, not all vaccines have turned out the same way — so how do we know whether a vaccine for Covid-19 can be developed reliably or not at all?

Fundamentally, an effective vaccine is a faithful representation of a part or all of the natural virus. It is administered by an injection, for example, and is absorbed by immune cells, which transport it to lymph nodes around the body. Here, little bits of the absorbed vaccine are shown to many immune cells, such as T-cells and B-cells, and some of these will be activated (if they match those bits of absorbed virus carefully). These cells will quickly multiply, producing antibodies and “memory cells” that can linger in the body for many years.

Later on, if the person is infected by the natural virus, a similar procedure occurs. The virus is absorbed by immune cells and transported to the lymph nodes, where the old memory cells are reactivated. These can quickly multiply and produce antibodies again, to fight off the virus before it can cause disease. Effective vaccines typically do not stop a recipient from being infected altogether, but they prevent a recipient from developing the disease caused by the virus.

Understanding the immune response to a virus can help direct development of the vaccine. In the case of Covid-19, there are several pieces of information we can make use of.

First, the way the virus mutates can tell us whether a vaccine will activate the same memory cells that can destroy the natural virus. If there are many strains of the natural virus, which appear very different to the immune system, the possibility that memory cells from the vaccine can recognise and destroy the virus becomes less likely. Effective vaccines for the coronavirus may be easier to develop than vaccines for many other viruses, because its mutation rate is fairly slow – thanks to special enzymes in coronaviruses (called exoribonucleases), which most viruses don’t have, and which proofread new mutations and fix most of them.

Second, the way the immune system usually responds to the virus can tell us whether the virus can be cleared from the body at all. A pessimistic scenario is one where the virus infects humans, finds cells to target quickly, and uses them to multiply very rapidly in the body, accumulating countless new mutations before immune cells can absorb it and take it to the lymph nodes. That is the case for HIV, which patients cannot clear from their own bodies, and for which a safe and effective vaccine has eluded scientists for decades. Even though there is still a great deal we are learning about the disease, this pessimistic scenario is less likely for Covid-19 because most patients do seem to be able to clear the virus from their body and recover from the disease.

These factors bode well for the prospects of an effective vaccine, but they are not all. We knew much of this in March, so why was it that even in late April, forecasters said there was only a 5% probability that a vaccine would be approved in the US before April 2021, with enough doses to vaccinate 25 million people, but they now believe that probability is 49%?

The fact that forecasts can shift so much so soon is more of a feature of forecasting than a bug. Many events that we forecast depend on whether other events happen, so just as my chances of being hospitalised are far greater if I’ve just fallen off a tree than if it was any random day, the approval of a vaccine becomes more and more likely if the vaccine succeeds in each phase of trials. When unlikely events come true, they make other events that are tied to them more likely.

Happily, the events of the last few months mean we can predict with some more confidence whether the trials will pan out as planned, and if the vaccines will be effective and safe.

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Often, large obstacles in vaccine development have come during the undertaking of trials. During phase III trials, participants are randomly given a vaccine or placebo, and researchers note the difference in the chances of disease between the two groups. But that difference would be undetectable if the outbreak was contained or sporadic, because few participants would be exposed to the virus at all.

We now know that is unlikely to be a problem for Covid-19, since the pandemic is still pervasive and participants are being recruited in hotspots around the world as they develop. Many thousands of people have already joined for the phase III trials of many frontrunning vaccines and recruitment is almost complete for Astrazeneca’s trial.

Even if a trial were feasible, though, it’s not guaranteed that a vaccine candidate would be effective or safe. It will be months until we know if the frontrunner vaccines will actually prevent the disease, when results from phase III trials become available. So far, we can only base our predictions on the data that is available from animal research and some phase I and II trials, which tell us whether the vaccines have triggered some immune response and what their side effects were, for a limited demographic.

When it comes to Covid-19 vaccines, some reviewers and experts (such as Hilda Bastian, Florian Krammer and Derek Lowe) have written detailed summaries of the data from phase I and II trials so far, and the results are broadly encouraging. The frontrunner vaccines trigger an immune response, people produce working antibodies and T-cells to them, and don’t exhibit major side effects.

But there are still caveats: these trials were very small, most vaccines required boosters, and mild side effects were common. Since the participants were mostly young and healthy, that could become a problem when the vaccine is then tested in a wider demographic. Fortunately, some vaccines, such as by Pfizer and Moderna, have been tested in elderly people, and they did not show significant side effects. Still, it is difficult to compare the results of phase I and II trials between different vaccines, because the numbers of participants were low and the doses of each vaccine varied in each trial.

But, judging from the results so far, we can rule out some worst-case scenarios: that vaccines wouldn’t trigger any immune response at all, or that they would frequently cause serious side effects. The results so far provide some cautious optimism about the prospects of these vaccines; but squeezing much further interpretation out of this data, which is limited and preliminary, is probably premature.

Having examined all this evidence, how do we put it together to answer the original question: how long will it be until there are enough doses of an approved vaccine for Covid-19 for 25 million people (in the US)?

Useful forecasts tend to not give single specific estimates of when events might occur (such as simply saying they will happen in December), but give a series of predictions. Even though some time periods will be most likely, we would also want to find out when things will occur if not then. So a useful exercise may be to imagine three forecasts – an optimistic timeline, a pessimistic timeline, and in-between “Goldilocks” timeline.

Here’s how those might play out.

In an optimistic timeline, a majority (say 60%) of the early vaccine candidates are on track to succeed. Even though this likelihood is far higher than the average proportion of all trialled drugs that are approved over all phases of trials (around 10%), the biology of the virus and promising results so far suggest that this anchor should be updated. Moreover, the pandemic continues to be pervasive, so a smaller number of participants need to be recruited to detect the effect of a vaccine, and phase III trials take much less time than usual.

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So perhaps one or two of the vaccines that started phase III trials very early (Astrazeneca, Pfizer or Moderna) are demonstrated to be safe and effective in key arms of the trials. And owing to demand and perhaps political pressure, they are authorised for emergency use soon after the companies stated they would submit applications (between September and December). Vaccine manufacturers quickly manage to produce tens to hundreds of millions of doses of these vaccines as they have claimed they will have by the end of the year. And the approvals process takes only weeks to a couple of months, because of rolling reviews.

This would place the date that 25 million doses of approved vaccines are available in the US sometime around January 2021. Although not everything went perfectly in this timeline and lots of vaccines failed, most things went well for at least one or two early vaccines. What would happen if they didn’t?

In a pessimistic timeline, only a minority (say 10%) of early vaccine candidates will succeed. It turns out that several of the vaccine candidates show severe side effects in the elderly in phase III trials. A few of the vaccines, alarmingly, also cause rare side effects (in trials or after emergency use authorisation). Pharmaceutical companies and regulators decide to scrutinise vaccine applications for much longer than in the optimistic timeline, and err far more on the side of caution until they are unequivocally shown to be safe.

Simultaneously, there are geopolitical setbacks or disasters that affect manufacturing and transport, or perhaps far larger doses are required than anticipated. Even more unluckily, the vaccines that do eventually get approved turn out to be the ones that are more difficult to manufacture at scale.

This would place the 25 million doses date sometime around June 2021, if not later. Distressingly, lots of things went wrong in this timeline, but they were still somewhat realistic. Fortunately, because so many vaccines were in trials and vaccine funding was at its highest level ever, at least some vaccines succeeded less than two years after the disease was identified, but this was still much later than people had hoped.

Now we should synthesise the two scenarios, but striking a balance between them could be difficult. Perhaps we can pick apart the chances of each of the events in both scenarios to try to figure out the most likely timeline. Here is my thinking:

So far, the speed of trials and dose manufacturing has been much faster than anticipated, the preliminary results are quite promising, there are very many different types of vaccines in trials, and the ongoing pandemic means it will be unusually easy to recruit enough participants into trials. The biology suggests that an effective vaccine is very achievable, the worst-case side effects are likely to be rare, and the urgency has already sped up the approvals procedure. At the same time, low efficacy and mild-to-moderate side effects could be a problem for several of the vaccines in trials, and unforeseen setbacks in manufacturing or approvals will probably occur for some of the vaccines.

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My view, then, is somewhere between these scenarios, with the most likely outcome being that vaccines will be approved and available in that quantity around February 2021, given what we know or can estimate so far.

Note that this doesn’t mean it would take until then for the public to receive Covid-19 vaccines. If a vaccine is cleared for emergency use authorisation, it could be prescribed to treat or prevent infections as a sort of experimental drug, before it might be approved.

The chances that no vaccine is approved before 2022 is probably fairly low, given the large number of vaccines in trials, but it also includes scenarios where vaccines would take many years to be approved, because of unforeseen or rare events. All in all, these are the chances that I would place on vaccines becoming approved and available in those large quantities in each time period: before 1 October 2020 (1%), between 1 October 2020 and 31 March 2021 (58%), between 1 April 2021 and 30 September 2021 (32%), between 1 October 2021 and 31 March 2022 (6%), not before 1 April 2022 (3%).

With a concrete set of predictions, then, this finally brings us to the end of the forecast, for the time-being. Events of the coming months, including results from phase III trials, will mean we can revise and refine our predictions; but many questions will remain.

How many vaccines will be approved? How effective will the first-approved vaccines be? Will people need to take boosters or combinations of vaccines? How will the vaccines be distributed? How long will it take to achieve herd immunity with vaccination? How long will it take for the disease to be eradicated globally; and is that even possible in our lifetimes?

The momentous day a vaccine arrives will feel revolutionary – a triumph of modern science over suffering. But with all the questions that remain and all that remains to be done, history suggests that it will be just one more hard-won battle in humanity’s long war against infectious disease.

But the big hope has always been the vaccine. At some point, we’ll develop a vaccine that works, we’ll build factories that can churn out millions of doses a day, and then we’ll all be set free. That’s the way out. If you’ve been anything like me, you’ve had that as a sort of promised land. I kind of imagine a great hand emerging from a cloud to deliver it, like God in a Terry Gilliam animation, with a plainchant choir singing in the background.

That hope is important, so you may have been alarmed if you read something in the last few days that seemed to say the hope was false: that herd immunity is impossible, and that vaccines won’t work, because immunity to Covid-19 only lasts a few months. “With coronavirus antibodies fading, vaccine hopes fade too,” said one particularly doom-laden headline. “Immunity to the coronavirus may only last a few months,” says another.

This comes off the back of a preprint from scientists at King’s College London, which looked at 64 patients who had had coronavirus (and 30 uninfected controls), and tracked their level of antibodies in the months after infection. It did, indeed, find that in a lot of patients — the ones who’d had a milder case of the disease — the number of antibodies in the blood decline quite quickly.

What that doesn’t mean, necessarily, is that there is no long-term immunity, or that vaccines are pointless, or that our only hope is for treatments. Let me try to explain why.

First, it absolutely is the case that with many coronaviruses, reinfection is possible. (Although we call Covid-19 “the coronavirus”, there are many others. There are four different seasonal coronaviruses that cause the common cold; SARS and MERS, much more severe diseases, were both coronaviruses too.) 

With the seasonal cold coronaviruses, says Rupert Beale, group leader at the Crick Institute’s Cell Biology of Infection laboratory, about 90% of people have had at least three of them by adulthood, and will, on average, be reinfected with each of them about once every five years.

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Babak Javid, a professor of immunology at the University of California San Francisco, agrees. But both of them make an important point: just because you can be reinfected, doesn’t mean that the reinfection is as bad as the original. Javid says that “the only definitive data we have with immunity and coronaviruses” comes from studies from a few decades ago, so-called “human challenge” studies, in which people were deliberately given the common cold and then their immune responses were tracked. 

Crucially, they found that if patients had detectable levels of antibodies before they were given the virus, they were immune. But, as you’d expect, people who didn’t have the antibodies got a cold — and then developed antibodies. The studies found, as with the current coronavirus, that the number of antibodies in the bloodstream then tailed off rapidly. 

A year later, the scientists tried infecting them again. They “were virologically affected”, says Javid – that is, if you swabbed them and tested for a virus, you would find it — but “they had no symptoms whatsoever, even in people with no antibody response”. The period in which they were themselves infectious appears to have been much shorter, as well.

Part of what’s going on here is that antibodies are only part of your body’s immune response to infection. Antibodies are proteins that latch onto infectious agents like viruses and bacteria and destroy them; they are produced by cells in your blood called B-cells. The precise shape of an antibody determines whether it will be able to destroy an invader. Very roughly, if an antibody turns out to be effective at killing some virus in your bloodstream, your B-cells will start producing loads more of that antibody to kill the virus. Then those antibodies will hang around in your blood, and your B-cells will “remember” how to make them, so next time the virus turns up, your body will be ready to fight them off.

But there’s more going on. There are also T-cells. Again, very roughly (and with apologies to Dr Beale if I’ve misunderstood his explanation), there are two kinds of T-cell. One helps B-cells produce antibodies. The other, “killer” T-cells, detect the presence of (usually) virus in infected cells of your body, and then kills those cells. They’re important in this story.

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“Broadly speaking,” says Beale, “antibodies prevent infection; killer T-cells help you get over disease.” Just like antibodies, killer T-cells have disease-specific responses – if you have one of the common cold coronaviruses, your body will have a T-cell response to that coronavirus.

That is, probably, part of why — even in people who have no detectable antibodies — reinfections are much less severe than first infections. You may not have enough antibodies to prevent you getting the disease in the first place, but you do have the T-cell response to fight it off quickly and easily. It is very possible, says Beale, that that is what will happen with Covid-19. “It’s behaving exactly as you’d expect for a respiratory coronavirus,” he says. Javid points out that in both SARS and MERS there is a very strong T-cell response “even five or 10 years later”.

There’s another point, which is that the tests used to detect antibodies are (deliberately) not very sensitive. The tests are designed to avoid false positives, because telling someone that they’ve had the disease and are immune when they’re not is much more dangerous than telling them that they’re not immune when they are. So the threshold for a “positive” response is quite high.

The necessary tradeoff is that there are more false negatives. By analogy: say you’re trying to decide whether someone is a Terry Pratchett fan. You set up a very simple test: you ask them “how many Terry Pratchett books have you read?” Then you set a minimum threshold.

If you set the threshold very low, say one or two, you’ll accurately identify all the fans, but you will also let in a lot of non-fans who just happen to have read Good Omens. Whereas if you set it very high, say 15, you’ll accurately weed out all the non-fans, but you might miss out on loads of real fans who are still working their way through the Discworld series for the first time. This is a zero-sum game: setting your threshold higher means more false negatives; setting it lower means more false positives. It’s unavoidable.

The same goes on with antibody tests. If you want to be more sensitive (get fewer false negatives), you can lower your threshold, but that means you’ll have more false positives; if you want to be more specific (fewer false positives), you raise your threshold, but that means you’ll have more false negatives. Unless you develop a new and better test, there is no third option, The tests have usually gone for specificity, rather than sensitivity.

That’s probably wise, but it presents a problem in that even very low levels of antibodies may offer protection. “In some monkey studies where they re-challenged,” says Javid — meaning giving the virus to monkeys who’d already had it — “very very low levels of antibodies were protective.” A lot of the tests use cut-offs that are higher, he says, “than what animal studies say are protective”. 

All that said, it probably is the case that people who’ve had milder cases will have antibody responses that wane quite quickly, in months rather than years, according to both Javid and Beale.

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It’s important to say that this doesn’t mean that vaccines won’t work. For one thing, says Javid, vaccine immune responses are “both qualitatively and quantitatively different” from immune responses to natural infection, when it comes to both antibodies and T-cells. That’s not a good thing or a bad thing, necessarily; it could be either, and “there’s no way to tell a priori”. But it does mean that it’s perfectly possible that natural infection could cause this tailed-off antibody response, while a vaccine has a more long-lasting one; or it could be the other way around. Or they could be largely the same. We’ll just have to wait and see, although the early noises from Oxford and elsewhere seem largely optimistic.

What it probably does mean, according to Beale, is that the most likely outcome is that Covid-19 becomes “the fifth seasonal coronavirus”. Assuming that a mild case of the disease only sparks a relatively short-term immunity, but that reinfection with the virus is far less dangerous because of the T-cell response (or whatever else is going on), then once everyone’s immune system is prepared for it, as with the common cold coronaviruses, we could see it going around as an inconvenient but not devastating seasonal illness. “If you’re vaccinated or infected, then it’ll be much less severe,” he predicts. “I’ll be genuinely surprised if that’s not where we end up.”

(He notes, however, that he has been genuinely surprised once already by Covid-19, specifically by the effectiveness of the drug dexamethasone in treating it. It’s still a novel disease and we shouldn’t get complacent that we know everything about it.)

Javid agrees. “This was predictable,” he says. “We kind of knew this was going to be the case months ago, it’s just that now we’ve had long enough to check.”

Even if we don’t ever eradicate the disease, we will probably end up in a place where we can live with it. In the meantime, though, it’s still absolutely crucial that we control the disease. Beale in particular says that “policy-wise, it’d be completely insane to let it get out of control now,” because “by this time next year” it’s likely that we will have an effective and widely available vaccine. “Better to lock down even at considerable economic cost and wait for that,” he says, although he acknowledges the calculus changes if the vaccine will be much longer coming. 

Javid adds that “As with everything Covid, it’s going to come down to how well we protect our vulnerable population,” which in the UK at least isn’t something we’ve conspicuously excelled at.

So there’s no need to panic; it seems to be unfolding as expected. I don’t want to be too harsh on anyone for the perhaps over-alarmist reporting; science writing in a fast-moving pandemic is bloody hard (I’ve discovered). But, so far, at least, I don’t think we need to start worrying that vaccines won’t work or that we’ll all be getting a life-threatening course of Covid-19 every calendar year. The hope that we’ll get out of this in a reasonable timescale, and life will return to something relatively normal before we’re all too old to enjoy it, is still very much there.