Statewide shutdowns across the country may have prevented millions of coronavirus infections in the USA, according to a study published Monday.
Researchers found the USA may have been able to avoid an additional 4.8 million confirmed coronavirus cases, which translates to about 60 million more infections, as a result of statewide lockdowns and mandated social distancing restrictions, according to the report published in the peer-reviewed scientific journal Nature.
Infections were much higher than confirmed cases, they argued, because many people didn't have access to a coronavirus test or didn't go to their doctors to obtain one. The study documented changes in testing procedures and availability, as well as differences in case detection across the country.
Johns Hopkins University reported more than 1.9 million confirmed coronavirus cases and more than 110,000 deaths as of Monday.
The study’s authors used a “reduced-form” technique more commonly used to measure economic growth rates. They argued that, similar to COVID-19 infections, economic output generally increases exponentially as a result of policies and other conditions.
The study looked at 1,717 local, regional and national policies, including travel restrictions, the cancellation of events, the closing of schools, retail and religious gatherings, quarantines and other emergency declarations, from early April.
"They’re using economic growth as a proxy for interconnectedness, and it’s the interconnectedness that drives the epidemic," said Dr. Kevin Dieckhaus, chief of infectious diseases at University of Connecticut Health.
Dieckhaus expects the USA will be able to decouple economic activity and case transmission as some businesses restructure office settings to promote social distancing, schedule constant disinfecting and require a mask.
A separate study, also published Monday in the journal Nature, found such lockdown methods may have prevented more than 3 million deaths across 11 European countries.
Both studies contribute to the growing evidence that national and regional lockdowns helped prevent coronavirus transmission and infection. Experts are concerned about a second wave of cases as the USA begins to ease restrictions and reopen the economy.
"The lockdown measures have served an important role in our society to prevent and mitigate unabated spread of the virus probably saving many millions of lives in doing so," said Michael Mina, assistant professor of epidemiology at Harvard T.H. Chan School of Public Health.
He's concerned the millions of confirmed cases prevented by social distancing restrictions in the spring may reappear in the fall. Most seasonal coronaviruses thrive in the fall, then begin to settle down in February and March.
"We have yet to experience this particular novel coronavirus during a season when it's usually most transmissible, and that’s a scary thought," he said.
Dieckhaus said the fall may bring more cases as the physical properties of the coronavirus prefer the cold, dry weather and more people spend less time outdoors in the well-circulated air. He said officials and residents have the power to manage cases by upholding preventive measures.
"The idea with all these changes is to continue the economic activity but doing it in a way that doesn't transmit the virus," he said.
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This article originally appeared on USA TODAY: COVID-19: US lockdown prevented 60M coronavirus infections, study says