Wearing a mask decreases virus strength if infected.

An increasing amount of observational evidence suggests that a mask could protect you from developing a serious case of COVID-19 — by cutting down on the amount of virus that takes root in your body.  There is an array of evidence suggesting that masks protect the people wearing them, lessening the severity of symptoms, or in some instances, staving off infection entirely.

In other words, people wearing face coverings will take in fewer coronavirus particles, making it easier for their immune systems to deal with the infection. The links between masking and milder disease haven’t yet been proved as cause and effect; however a growing body of evidence points that way.

Some indirect data has been accumulating from animals and from people as well. Researchers have tentatively estimated that about 40 percent of coronavirus infections do not produce any symptoms. But when some people wear masks, the proportion of asymptomatic cases seems to skyrocket, reportedly surpassing 90 percent during one outbreak at a seafood plant in Oregon. Wearing a face covering doesn’t make people impervious to infection, but these trends of asymptomatic cases could suggest that masks lead to milder disease, potentially reducing hospitalizations and deaths.

Particularly compelling is the data from cruise ships, which pack big groups of people into close quarters. More than 80 percent of those infected aboard Japan’s Diamond Princess in February — before masking had become common practice — came down with symptoms. But on another vessel that left Argentina in March, and on which all passengers were issued surgical masks after someone onboard came down with a fever, the level of symptomatic cases was below 20 percent.