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Stop looking for coronavirus ‘super-spreaders’ There are lots of bad and dangerous ideas circulating about contagious diseases

Coronavirus has now spread across 70 countries (Photo by PHILIPPE LOPEZ/AFP via Getty Images)

Coronavirus has now spread across 70 countries (Photo by PHILIPPE LOPEZ/AFP via Getty Images)

March 3, 2020   6 mins

The word “influencers”, which nowadays just means “Instagram people who shill for package holiday companies”, came from an idea sourced from epidemiology. That theory is that some non-famous people have disproportionate influence in the spread of ideas; if marketers can reach them, then they will spread the good word of the brand around, more effectively than using traditional advertising.

Unfortunately — for marketers, at least — the idea of influencers, as so many things, is (to paraphrase Adam Kucharski’s excellent book The Rules of Contagion) either true and not interesting, or interesting and not true.

Obviously there will be differences in how effective some people are at spreading ideas. People who have lots of friends might be more capable of spreading them than people who have very few, for instance. In that sense, “influencers” — people who spread ideas more than the average — clearly exist. It’s true, but not interesting. 

But the idea that some are hugely more effective — that they will spread ideas to thousands or hundreds of thousands more people than the average — is not borne out by the facts. It’d be interesting, but it’s not true. Some people may be a bit better at spreading ideas, but not much, and it’s very hard to work out in advance who they are.

As Kucharski explains, the idea of influencers comes from the maths of contagion. You can use the same numbers to explain how memes spread as you do to explain how viruses do. The equivalent of an influencer in viral contagion is a “super-spreader”.

There’s a bit of a panic going on about one such in Britain. There’s a “hunt” for a “feared coronavirus ‘super-spreader’”, who is believed to be the source of at least four infections.

The trouble is that this idea of a “feared super-spreader” implies that they’re somehow different. Kucharski refers to Malcolm Gladwell’s book The Tipping Point, in which Gladwell solemnly explains that 168 supposed super-spreaders in a 1981 gonorrhea outbreak were not “like you and me”; they were “out every night”, “had vastly more sexual partners” and so on.

But again it doesn’t really stand up. In the gonorrhea case the main difference was length of time without treatment — people from deprived backgrounds who had worse access to medical care, so had more time to spread the disease despite being less sexually active, ended up passing it on. 

And in general, the key thing about super-spreaders is not that they’re special but that they’re undetected. Kucharski mentions the Ebola outbreak in central Africa in 2013, where there was great study of the super-spreader phenomenon. One feature stood out, he says, but “it wasn’t a particularly helpful one … Put simply, the people driving the epidemic were generally the ones the health authorities didn’t know about.” If you’re undiagnosed and unknown to the health service, but infectious, then you have a longer window to infect people.

So far so obvious, I guess. But as Kucharski points out, the idea of “super-spreaders” sounds like someone is to blame. And if you start blaming people, they’ll start hiding. It’s a useful (if badly named) technical term for epidemiologists, but it’s not helpful if the media start using it.

The trouble is, we in the media have a need for simple narratives and simple solutions. It’s understandable but problematic. For instance, in the Times, Clare Foges argues that “the ‘me’ generation” is too selfish to take steps to reduce the spread of coronavirus: in the Second World War, “public information campaigns resounded with Old Testament authority: Dig for Victory! Make Do and Mend!” and they were obeyed: “The man in Whitehall really did know best and when he spoke people listened.”

Now, though, we’re all too individualistic — disinclined “to suffer any sacrifice for the sake of the herd”, as she put it. “The proliferation of rights and conveniences has made many of us rather self-indulgent creatures,” Foges says, and isn’t the only person to think this: Gaby Hinsliff, writing in the Guardian a few days ago, made a similar case. They both point to the rise of the anti-vaccination movement as an example of selfishness: “we all know what has happened to vaccination levels across the west,” says Hinsliff; “I’m-all-right-Jack anti-vaxxers embody the selfish conclusion of individualism,” says Foges.

I want to gently push back against this idea. For one thing, I don’t think it’s helpful to imagine anti-vaxxers as motivated by selfishness; the decline in vaccination rates followed a gigantic scare that the MMR vaccine caused autism. The scare was false and driven by fraud (and media credulousness), but I think it’s probably more accurate — and more charitable — to assume that most non-vaccinating parents are motivated by fear, rather than selfishness. 

More generally, there just isn’t much evidence that this generation is a “me” generation anyway. The concept has largely come from the work of Jean Twenge, also famous for her work purporting to show that social media and smartphones are damaging the youth: but like that work, it is highly disputed. Most claims of major personality differences between generations are shaky. Ironically, it seems to be a stable fact that the older generation tends to think the younger ones are feckless or selfish. I would be greatly surprised if the spread of coronavirus were noticeably affected by intergenerational differences in narcissism. 

And it’s not as if there aren’t examples of past generations refusing to self-isolate, anecdotes to match those offered by Foges of Tenerife holidaymakers flouting the lockdown: as Anne Applebaum notes in the Atlantic, half of the residents of the pestilence-stricken town in Albert Camus’s The Plague “continued with business, with making arrangements for travel and holding opinions”.

The most famous “super-spreader” of all, Typhoid Mary, was repeatedly told she was spreading typhus, and twice quarantined, but refused to stop working as a cook and appears to have been responsible for about 50 cases and three deaths. She died in 1938, after a total of 30 years of enforced isolation, decades before the term “millennial” was even coined. 

I don’t know whether that sort of behaviour is more or less common now than it was in Mary Mallon’s day, or whether people were more likely to nobly sacrifice themselves in 1660 than they are now; my guess is any differences will be small and hard to detect, because people are people. But to some degree it doesn’t matter whether we are more or less selfish than we were; the question is whether we are too selfish now to self-isolate as required, however selfish our ancestors were.

Foges at least thinks we are, and that for that reason “the government must quickly open the box of measures which some will call draconian”, such as closing schools, shutting public transport systems, and putting whole towns in quarantine.

I’m not saying that she’s wrong, necessarily. I am just worried that the rise of coronavirus means that all of us in the opinion-slinging business are suddenly required to have thoughts on the best way to curb an epidemic, and I’m not sure that we’re the best placed to do so. We’re not epidemiologists or infectious disease specialists.

Earlier I tried to use Kucharski’s work rather than my own thoughts on the importance of super-spreaders; I hope I’ve represented his work fairly. Now I’m going to use the thinking of a senior infectious disease specialist who I spoke to a couple of weeks ago. The disease has spread rapidly since then and the situation has changed, but a few things he said stuck with me and are, I think, still relevant.

One thing was that closing the schools sounds like a brilliant idea, and it may be necessary, but it comes at significant costs. Not only economic costs (as if “only” economic costs don’t themselves have serious consequences for people’s lives) but in terms of our response to the pandemic itself, because many healthcare workers will have children in schools.

The NHS is already overstretched, before the coronavirus has even arrived in force. If some double-digit percentage of nurses and doctors can’t make it to work because their kids’ schools are closed that will make things harder. It may reduce infection and so ease the overall burden on the healthcare system, but it’s not entirely obvious.

Similarly, he pointed out, shutting down the public transport system means healthcare workers not getting to work. Quarantining towns or shutting borders means drugs and other medical supplies not getting where they’re needed. Maybe all this is a price worth paying, but I wouldn’t want to be the one making the call, without some serious in-depth knowledge about logistical pathways, infection patterns and staffing levels. 

This isn’t a call for radical scepticism, or for blindly trusting the government. I’m sure we can make good decisions — the infectious disease specialist I spoke to was forceful in saying that public health bodies are not powerless, that we have the ability to push the probabilities towards more mild outcomes. “We have to be really calm and logical and not panic,” he said. 

But in the media we are influencers, not in the true-but-not-interesting-or-interesting-but-not-true Gladwellish sense but in the Instagram shills sense: we have platforms, and can broadcast stuff out. I think our responsibility at this point is to stay calm, not look for simplistic stories like “super-spreaders” and selfish millennials, and be careful about calling for draconian measures. Ideas spread like diseases, remember, and that goes for bad ideas just as much as good ones.


Tom Chivers is a science writer. His second book, How to Read Numbers, is out now.


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