The C.D.C. and leading experts have concluded, using different scientific methods, that as many as 90 percent of Americans are still vulnerable to infection.
By Donald G. McNeil Jr.
In the last two weeks, leading epidemiologists from many respected institutions have, through different methods, reached the same conclusion: About 85 to 90 percent of the American population is still susceptible to SARS-CoV-2, the virus causing the current pandemic.
The number is important because it means that “herd immunity” — the point at which a disease stops spreading because nearly everyone in a population has contracted it — is still very far off.
The evidence — both from antibody testing and from epidemiological modeling — runs strongly counter to a theory being promoted in influential circles that the United States has either already achieved herd immunity or is close to doing so, and that the pandemic is all but over. That conclusion would imply that businesses, schools and restaurants could safely reopen, and that masks and other distancing measures could be abandoned.
“The idea that herd immunity will happen at 10 or 20 percent is just nonsense,” said Dr. Christopher J.L. Murray, director of the University of Washington’s Institute for Health Metrics and Evaluation, which produced the epidemic model frequently cited during White House news briefings as the epidemic hit hard in the spring.
That belief began circulating months ago on conservative news programs like those of Rush Limbaugh and Laura Ingraham. It has been cited several times by Dr. Scott W. Atlas, President Trump’s new pandemic adviser. It appears to be behind Mr. Trump’s recent remarks that the pandemic is “rounding the corner” and “would go away even without the vaccine.”
But it is also gaining credence on Wall Street and among some business executives, said prominent public health experts, who consider the idea scientifically unfounded as well as dangerous; its most vocal adherents are calling for mask-wearing and social distancing to end just as cold weather is shifting social activity indoors, where the risk of transmission is higher.
Even in places where the pandemic hit especially hard — a French aircraft carrier, the Brazilian city of Manaus, the slums of Mumbai and a neighborhood in Queens, N.Y. — infections did not noticeably slow down until almost 60 percent of the inhabitants were infected. And even those levels may not suffice, given that cases are increasing again in Brazil and in Brooklyn areas that had seen cases spike and then drop off.
“Immunity in 2020 is no closer to being just around the corner than prosperity was in 1930,” said Dr. Thomas R. Frieden, a former director of the Centers for Disease Control and Prevention. “The route to immunity without a vaccine would be through graveyards filled with hundreds of thousands of Americans who did not have to die.”
In April, in an opinion piece for The Hill that endorsed letting the virus circulate, Dr. Atlas cited the conventional wisdom that herd immunity requires that about 60 percent of people have antibodies. But last week he said on “The Ingraham Angle” that “most of the immunity for this virus is felt to be due to T-cell immunity” and speculated that such immunity was why children rarely became dangerously ill and why Asian countries did well against the virus.
(Many reputable medical experts think that children, who suffer many colds, may be protected in that regard. But Asian countries contained the virus through early travel bans, lockdowns, masks and rigorous contact tracing.)
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