Read: You’re likely to get the coronavirus
With the peak of the pandemic still weeks away, the time hadn’t come yet for stricter measures, Johnson and his advisers said. They worried about “behavioral fatigue”—if restrictions come into force too early, people could become increasingly uncooperative and less vigilant, just as the outbreak swings into high gear. (As of yesterday, the U.K. has identified 1,391 cases, although thousands more are likely undetected.) And while suppressing the virus through draconian measures might be successful for months, when they lift, the virus will return, said Sir Patrick Vallance, the U.K.’s chief scientific adviser.
To avoid a second peak in the winter, Vallance said the U.K. would suppress the virus “but not get rid of it completely,” while focusing on protecting vulnerable groups, such as the elderly. In the meantime, other people would get sick. But since the virus causes milder illness in younger age groups, most would recover and subsequently be immune to the virus. This “herd immunity” would reduce transmission in the event of a winter resurgence. On Sky News, Vallance said that “probably about 60 percent” of people would need to be infected to achieve herd immunity.
Read: What will you do if you start coughing?
Almost immediately, the supposed plan came under heavy criticism, coupled with confusion that public-health and science advisers would recommend this strategy. Herd immunity is typically generated through vaccination, and while it could arise through widespread infection, “you don’t rely on the very deadly infectious agent to create an immune population,” says Akiko Iwasaki, a virologist at the Yale School of Medicine. And that seemed like the goal. In interviews, Vallance and others certainly made it sound like the government was deliberately aiming for 60 percent of the populace to fall ill. Keep calm and carry on … and get COVID-19.
That is not the plan.
“People have misinterpreted the phrase herd immunity as meaning that we’re going to have an epidemic to get people infected,” says Graham Medley at the London School of Hygiene and Tropical Medicine. Medley chairs a group of scientists who model the spread of infectious diseases and advise the government on pandemic responses. He says that the actual goal is the same as that of other countries: flatten the curve by staggering the onset of infections. As a consequence, the nation may achieve herd immunity; it’s a side effect, not an aim. Indeed, yesterday, U.K. Health Secretary Matt Hancock stated, “Herd immunity is not our goal or policy.” The government’s actual coronavirus action plan, available online, doesn’t mention herd immunity at all. “The messaging has been really confusing, and I think that was really unfortunate,” says Petra Klepac, who is also an infectious-disease modeler at the London School of Hygiene and Tropical Medicine. “It’s been a case of how not to communicate during an outbreak,” says Devi Sridhar, a public-health specialist at the University of Edinburgh.