It’s the biggest question in the world right now: is Covid-19 a deadly disease that only a small fraction of our populations have so far been exposed to? Or is it a much milder pandemic that a large percentage of people have already encountered and is already on its way out?
If Professor Neil Ferguson of Imperial College is the figurehead for the first opinion, then Sunetra Gupta, Professor of Theoretical Epidemiology at the University of Oxford, is the representative of the second. Her group at Oxford produced a rival model to Ferguson’s back in March which speculated that as much as 50% of the population may already have been infected and the true Infection Fatality Rate may be as low as 0.1%.
Since then, we have seen various antibody studies around the world indicating a disappointingly small percentage of seroprevalence — the percentage of the population has the anti-Covid-19 antibody. It was starting to seem like Ferguson’s view was the one closer to the truth.
But, in her first major interview since the Oxford study was published in March, Professor Gupta is only more convinced that her original opinion was correct.
As she sees it, the antibody studies, although useful, do not indicate the true level of exposure or level of immunity. First, many of the antibody tests are “extremely unreliable” and rely on hard-to-achieve representative groups. But more important, many people who have been exposed to the virus will have other kinds of immunity that don’t show up on antibody tests — either for genetic reasons or the result of pre-existing immunities to related coronaviruses such as the common cold.
The implications of this are profound – it means that when we hear results from antibody tests (such as a forthcoming official UK Government study) the percentage who test positive for antibodies is not necessarily equal to the percentage who have immunity or resistance to the virus. The true number could be much higher.
Observing the very similar patterns of the epidemic across countries around the world has convinced Professor Gupta that it is this hidden immunity, more than lockdowns or government interventions, that offers the best explanation of the Covid-19 progression:
“In almost every context we’ve seen the epidemic grow, turn around and die away — almost like clockwork. Different countries have had different lockdown policies, and yet what we’ve observed is almost a uniform pattern of behaviour which is highly consistent with the SIR model. To me that suggests that much of the driving force here was due to the build-up of immunity. I think that’s a more parsimonious explanation than one which requires in every country for lockdown (or various degrees of lockdown, including no lockdown) to have had the same effect.”
Asked what her updated estimate for the Infection Fatality Rate is, Professor Gupta says, “I think that the epidemic has largely come and is on its way out in this country so I think it would be definitely less than 1 in 1000 and probably closer to 1 in 10,000.” That would be somewhere between 0.1% and 0.01%.
Professor Gupta also remains openly critical of the Government lockdown policy:
“The Government’s defence is that this [the Imperial College model] was a plausible worst case scenario. I agree it was a plausible — or at least a possible — worst case scenario. The question is, should we act on a possible worst case scenario, given the costs of lockdown? It seems to me that given that the costs of lockdown are mounting, that case is becoming more and more fragile.”
She recommends “a more rapid exit from lockdown based more on certain heuristics, like who is dying and what is happening to the death rates”. She does not believe that the R rate is a useful tool in making decisions about government policies, as an R rate is “principally dependent on how many people are immune” and we don’t have that information.
She believes that deaths are the only reliable measure, and that the number of cases should not even be presented as it is so reliant on the amount of testing being done.
She explains the flare-ups in places like New York, where the IFR seems to have been higher than 0.1%, through a combination of circumstances leading to unusually bad outbreaks, including the infection load and the layout of the population:
“When you have pockets of vulnerable people it might rip through those pockets in a way that it wouldn’t if the vulnerable people were more scattered within the general population.”
She believes that longer-term lockdown-style social distancing makes us more vulnerable, not less vulnerable, to infectious diseases, because it keeps people unprotected from pathogens:
“Remaining in a state of lockdown is extremely dangerous from the point of view of the vulnerability of the entire population to new pathogens. Effectively we used to live in a state approximating lockdown 100 years ago, and that was what created the conditions for the Spanish Flu to come in and kill 50m people.”
Commenting on the Government response to the virus, she suggests it erred on the side of over-reaction not under-reaction:
“I think there’s a chance we might have done better by doing nothing at all, or at least by doing something different, which would have been to pay attention to protecting the vulnerable, to have thought about protecting the vulnerable 30 or 40 years ago when we started cutting hospital beds. The roots of this go a long, long way back.”
And she believes it is a “strong possibility” that if we return to full normal tomorrow — pubs, nightclubs, festivals — we would be fine, but accepts that is hard to prove with the current evidence:
“So what do we do? I think we weigh that strong possibility against the costs of lockdown. I think it is very dangerous to talk about lockdown without recognising the enormous costs that it has on other vulnerable sectors in the population.”
On the politics of the question, Professor Gupta is clear that she believes that lockdowns are an affront to progressive values:
“So I know there is a sort of libertarian argument for the release of lockdown, and I think it is unfortunate that those of us who feel we should think differently about lockdown have had our voices added to that libertarian harangue. But the truth is that lockdown is a luxury, and it’s a luxury that the middle classes are enjoying and higher income countries are enjoying at the expense of the poor, the vulnerable and less developed countries. It’s a very serious crisis.”