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Even while canceling mass gatherings, the U.K. is still aiming for deliberate ‘herd immunity’

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The U.K. will cancel mass gatherings beginning next weekend, The Guardian newspaper reported Friday night, after a wave of high-profile cancellations and pressure from the public and scientific community appeared to force the government’s hand.

The announcement came after British institutions, from football’s Premier League to the Queen, moved to cancel games and official engagements, despite official government policy that cancellations would do little to stem infections and would cause too large a disruption on public life.

It also followed statements from both well-known scientists and politicians criticizing Boris Johnson’s government’s strategy for fighting coronavirus, which takes a markedly different approach than most European governments and, despite Friday’s announcement, remains in place.

At the heart of that outcry: a policy to push for “herd immunity” to the virus, which would involve allowing at least 40 million Britons to become infected in the hopes of building up a long-term, society-wide resistance to the disease.

“Our aim is to try and reduce the peak [of the infections], broaden the peak, not suppress it completely,” Vallance told BBC Radio 4’s Today program on Friday. “Also, because the vast majority of people get a mild illness, to build up some kind of herd immunity so more people are immune to this disease and we reduce the transmission.”

For herd immunity to kick in, the U.K. government said that about 60{ce8ce7cc98bffdc4302011057a79600ea02c464c5536f1477c12acdb8bd79c00} of the population would need to contract the virus. At that point, the rate of transmissions drops enough to protect the remaining 40{ce8ce7cc98bffdc4302011057a79600ea02c464c5536f1477c12acdb8bd79c00} of the population from contracting the virus. But the strategy is also based around trying to manage which people are in that 60{ce8ce7cc98bffdc4302011057a79600ea02c464c5536f1477c12acdb8bd79c00}—in an ideal scenario, the government would want only those most likely to experience a mild illness to get infected. (The government has previously said, that in a worst case scenario, 80{ce8ce7cc98bffdc4302011057a79600ea02c464c5536f1477c12acdb8bd79c00} of the population might eventually contract the virus, above the German government’s estimate of 70{ce8ce7cc98bffdc4302011057a79600ea02c464c5536f1477c12acdb8bd79c00}.)

The U.K.’s approach means many healthy people in the country have to get the disease—while keeping the fatality rate as low as possible. It’s a marked break with the approach in much of the rest of the world, which is to stop people from getting coronavirus, period.

It’s also an approach that is based on the assumptions that COVID-19 will be a recurring, seasonal virus—like the flu—and that once you get the virus, you can’t get it again. If that’s the case—and those are very big ifs—there are usually two ways to manage a virus long-term. The first is through a vaccine, and if one doesn’t exist, the second is through enough people catching the virus, recovering, and being immune to re-infection, therefore making the virus much less common, and less of a risk to those who are vulnerable.

The problem is that this approach is still extremely risky, as multiple scientific experts pointed out.

“I’ve been talking to other academics, science journalists, private companies, & gov’t people all of today and still struggling to understand this,” Devi Sridhar, Chair of Global Public Health at the University of Edinburgh tweeted. “The gov’t seems to be following flu playbook strategy. But this is not the flu. COVID-19 is much worse & health outcomes are sobering.”

In the mean time, it’s likely impossible to completely sequester those who are vulnerable or know exactly who will be vulnerable in the first place. Herd immunity is difficult; in the case of measles, for example, it’s is only preserved through very high vaccination rates.

During the press conference on Thursday evening with Vallance, chief medical officer Chris Whitty, and prime minister Johnson, the government announced the country was moving to the “delay” phase for managing the virus, which includes attempting to lessen the pressure on the health system by flattening out the curve of cases and pushing the peak of the virus out to the warmer months, when respiratory viruses are typically not as viral.

That approach includes asking people with even very mild cough and flu symptoms to stay home, but stopped short of the measures seen in most other European countries and increasingly in North America, including closing schools and colleges.

The government said Thursday that it may have to impose these more stringent measures at some point in the future, but that doing so now would be premature, disrupting daily life before it was absolutely necessary, and risking the public would grow tired of complying with the restrictions and begin to ignore them just when the peak number of infections might be expected, based on the data the U.K. government has crunched.

It’s a strategy that relies heavily on mathematical modeling and a government behavioral insights team, known by the nickname the “nudge unit”, for their use of a psychological theory to “nudge” people towards certain behaviors—like paying their taxes, or staying home when they feel sick.

But the announced new measures, which are far less strict than those other nations’ have imposed, paired with the emphasis on herd immunity, also provoked staunch criticism from both well-known virologists and epidemiologists, and politicians, including Conservatives.

On the BBC’s Newsnight program, Conservative MP Jeremy Hunt, a former health secretary and foreign secretary, called the decision not to cancel large gatherings “surprising and concerning,” and said that given predictions the U.K. will reach Italy’s current infection rates in roughly four weeks, more extreme measures should be taken to prepare.

Meanwhile Rory Stewart, a former Conservative cabinet minister, called it a “very eccentric” tactic in an interview with CNN’s Christiane Amanpour, and said the government’s approach risked spreading the virus to the rest of the world, while underestimating the impact of the virus on the country’s own health system.

“Britain is trying to follow a theory of herd immunity. In other words they believe it’s impossible to get on top of this disease, and therefore you have to ultimately let it run through the population,” Stewart said.

“That is a very, very big choice. It’s not a scientific choice, it’s fundamentally a political choice. These are judgements about what the population are prepared to put up with, these are judgements about how long people are prepared to have schools closed, these are judgements fundamentally about economics.”

Stewart added that he thought the government had made the wrong judgement by not being transparent, and said that “when the public understands that implicit in this argument is that they would rather that people died earlier to prevent more people dying later, the public will be very troubled.”

“It is baffling,” tweeted Gavin Yamey, director of the Center for Policy Impact in Global Health at Duke University. “How does Vallance *know* that this is going to be an endemic seasonal virus? How does Vallance *know* that the best approach is to deliberately hope most people get infected? Where on earth is the evidence behind this very, very risky approach??”

The announcement of the government’s new strategy on Wednesday included a new policy that the NHS will stop testing for the virus outside of hospitals, leaving mild cases untested and unconfirmed. That would make it more difficult to determine when the population had indeed reached herd immunity, other than by extrapolating backwards from the fatality rate of confirmed coronavirus cases in hospitals.

But the lack of testing for mild cases, which are believed to be the vast majority, was also likely to distort the country’s fatality statistics, pointed out Lindsay Broadbent, an expert on respiratory virus infections at the Centre for Experimental Medicine at Queen’s University Belfast.

“Testing as many as possible is so important. South Korea are an excellent example of this,” she tweeted. “With the U.K. gov announcing they will restrict testing to more severe patients this will make isolation of infected difficult and will look like we have a high fatality rate!”

On Friday afternoon, the U.K. had 798 reported cases of coronavirus, a jump of more than 35{ce8ce7cc98bffdc4302011057a79600ea02c464c5536f1477c12acdb8bd79c00} from the previous day, with 10 fatalities.

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