Research: Distancing prevented almost 5M COVID-19 cases
Quarantine, canceled events and other restrictions prevented almost 5 million confirmed cases of COVID-19 in the U.S. alone, according to a study published Monday in the journal Nature.
Because confirmed cases are only a fraction of all cases, the U.S. likely averted almost 60 million total infections through these and other social distancing measures, said Andy Hultgren, a doctoral candidate at the University of California, Berkeley and a co-author on the study.
As of Monday afternoon, the U.S. had a little below 2 million confirmed cases of COVID-19, according to numbers kept by Johns Hopkins University.
Hultgren, who is pursuing a doctorate in agricultural and resource economics, said he was surprised at how consistent the rate of spread was in the six countries the team examined: U.S., China, South Korea, Italy, Iran and France.
“The second thing I found to be surprising was the magnitude of this infection growth rate in the absence of policy,” he said.
Without the policies, the number of infections rose 38% each day, he said. “This rate of spread implies that, without policy, the number of infections would double every two days.”
The authors estimated that across all six countries in the study, social distancing measures either prevented or delayed 62 million cases of COVID-19.
“I think the final conclusion is awesome — 62 million cases prevented or delayed. That really knocked my socks off,” said William Schaffner, a professor of preventive medicine and infectious diseases at the Vanderbilt University School of Medicine.
Schaffner, who did not work on the study, called the work, “very, very solid and very thoughtful.” He pointed out that it wasn’t just the infections averted that were important.
“If cases had not been delayed,” he said, “the stress on our health care system, which was already great, would have been even greater.”
The study team included analysts at UC Berkeley, the National Bureau of Economic Research & Economic Policy Research in Cambridge, Massachusetts, and a group in New Zealand.
The researchers examined the impacts of 1,717 local, regional and national policies enacted in the six countries in response to COVID-19.
They reached their estimates of cases delayed and prevented by employing mathematical techniques often used in economics to measure the financial impact of policies. The technique also has been used to examine influenza cases.
Schaffner said the study holds clear lessons for residents and policymakers in the U.S.
“As we open up and go forward into the new normal, we have to keep maintaining social distancing,” he said. “We have to keep the 6 feet between us. We need to maintain good hand-washing.”
He said that in the absence of a vaccine to protect people from infection, large activities — including religious services, concerts and sports events — will continue to pose a risk.
Although football games are held outdoors, less of a risk than indoor events, Schaffner said it’s not just the games themselves that must be considered. “It’s the travel, the tailgating, the restaurants, the parties,” he said. “All these things bring people together.”