The researchers looked at COVID-19 death rates across 198 countries and found that predictors of COVID-19-related mortality included age, sex ratio, obesity prevalence, temperature, urbanization, smoking, duration of infection, lockdowns, viral testing and contact-tracing policies, as well as public mask-wearing policies, the study’s abstract explains.
The report found that wearing masks is a very important factor in reducing death rates: the per-capita mortality rates in countries that weren't recommending masks increased each week by around 54%, compared to 8% in countries with government policies or cultural norms that supported wearing masks.
The study also found that the per-capita mortality rate tended to increase by just over 45% weekly in countries with social distancing restrictions but without mask policies.
The study has gone through the peer-review process but is still currently in the pre-print phase.
“What we found was that of the big variables that you can control which influence mortality, one was wearing masks,” Christopher Leffler of Virginia Commonwealth University, one of the study’s authors, is quoted as saying by multiple outlets.
“It wasn’t just by a few percent, it was up to a hundred times less mortality. The countries that introduced masks from the very beginning of their outbreak have had hardly any deaths,” he added.
The study also found the majority of countries with the lowest death rates were in East Asia and included South Korea and Japan, which quickly enacted mask-wearing policies when the coronavirus began to appear within their borders.
“You also have Taiwan, Hong Kong, Macau — there are lots of countries that used masks early on. Vietnam and Thailand are good examples — they’ve kept per capita mortality very low,” Leffler noted.
Despite the study’s compelling findings, the authors did admit that the research wasn’t entirely perfect, as it relied on publicly available information regarding COVID-19 deaths, which are defined and reported differently between countries.
A Cambridge University study released earlier this month also found that masks can greatly reduce COVID-19 transmission if they are worn by enough people.
"Our analyses support the immediate and universal adoption of facemasks by the public," lead author, Dr. Richard Stutt is quoted as saying in a June 9 news release.
"If widespread facemask use by the public is combined with physical distancing and some lockdown, it may offer an acceptable way of managing the pandemic and re-opening economic activity long before there is a working vaccine,” he added.
