Experts think that to reach herd immunity — the point at which the coronavirus can no longer spread widely — about 70 percent of a population must be immune, either through vaccination or surviving the infection. Some people, including President Trump, claim we’re nearly there.
Our colleague Donald G. McNeil Jr., who covers science, recently set out to determine how close the United States was to reaching that elusive milestone.
He asked three epidemic-modeling teams — the Prevention Policy Modeling Lab at Harvard’s T.H. Chan School of Public Health, the University of Minnesota’s Center for Infectious Disease Research and Policy, and the Covid-19 Projections website — to calculate what percentage of the country has been infected based on testing and death data from all 50 states.
Their responses were strikingly similar: They found that only 10 percent to 16 percent of Americans have had the virus, leaving up to 90 percent of the population vulnerable.
The numbers are in line with two other studies published last week. The Centers for Disease Control and Prevention, citing data from blood samples collected at labs across the country, said that less than 10 percent contained antibodies. And in a study published in The Lancet, Stanford University scientists examined almost 29,000 blood samples from dialysis centers and found antibodies in just over 9 percent of patients.
The theory that the U.S. may have already achieved herd immunity — and therefore we should get back to our regular lives — is circulating among conservative news programs and the Trump administration, and is gaining credence on Wall Street.
But these studies suggest herd immunity is still very far off.
“If we all took off our masks and went back into hanging out in bars and piling into the offices and subways, hundreds of thousands more of us would die,” Donald said.
Revisiting Sweden. Sweden became a lightning rod last spring when it refused to impose coronavirus lockdown measures. Now, as the country’s caseload remains surprisingly low, the question is whether it has found a sustainable balance, or whether the recent numbers are just a temporary anomaly.
After months of persistently driving down its virus numbers, New York City is witnessing a jump in virus cases — a troubling sign as the city takes some major steps toward resuming public life.
The city’s daily positivity rate, or the share of tests that come back positive, reached 3.25 percent on Tuesday, the highest it has been since June.
Officials are particularly concerned about eight neighborhoods in Brooklyn and Queens, including some predominantly Orthodox Jewish communities, which have accounted for about one-fourth of New York City’s new cases in the past two weeks, despite accounting for only about 7 percent of the city’s population.
The outbreak has emerged at a fraught, pivotal moment: Elementary schools reopened today, with about 300,000 children returning to classrooms for the first time since March, and indoor dining is set to resume tomorrow.
Mayor Bill de Blasio has said he would shut down the entire public school system if the city’s test positivity rate exceeded 3 percent over a seven-day rolling average. Based on the current trend, the city could reach that threshold quickly — and if schools are forced to close, it could take weeks for them to reopen, according to the city’s health officials.
Ontario, the most populous province in Canada, reported 700 new infections on Monday, its highest one-day total.
Kenya extended its nationwide curfew for two months. In an address to the nation, President Uhuru Kenyatta said bars and nightclubs could reopen but schools will remain closed.
The Netherlands tightened its coronavirus restrictions as cases quickly rose, warning that its most severe wave yet was likely to get worse.