New York City’s lockdown in the spring reduced the spread of the coronavirus by 70 percent, but more consistency with mask-wearing would have brought it down even further, according to a forthcoming study from Columbia University’s Mailman School of Public Health and the New York City Department of Health and Mental Hygiene.
The city began closing public schools on March 15 and imposed stay-at-home orders for everyone except essential workers the following week. Restrictions remained in place until June, when the city began gradually reopening while keeping indoor dining and other high-risk activities off limits.
According to the study, which has not yet been peer-reviewed, reducing contact rates by closing schools and telling people to stay home “likely contributed to the largest reduction in transmission in the population overall.” But masks also played a crucial role, the researchers wrote. New York City began requiring face coverings on April 12, which helped reduce transmission by an additional 7 percent overall, and by 20 percent among people 65 or older.
Those statistics reflect the reality that masks aren’t always worn correctly — or at all. If everyone in the city modeled their mask-wearing behavior on older adults, overall transmission could be reduced by as much as 32 percent, the scientists wrote.
“Improving effective use of face coverings, especially among younger people, would significantly mitigate the risk of a resurgence in covid-19 infections during reopening,” Jeffrey Shaman, a professor of environmental health sciences at Columbia and one of the main authors of the study, said in a statement. “It’s crucial that we find ways to boost consistent and correct mask use in settings where social distancing is not possible.”