UCSF Study Finds Masks Protect Wearer More Than Previously Thought

A masked pedestrian pauses near the Amazon headquarters on March 10, 2020 in downtown Seattle, Washington.
Photo credit John Moore / Getty
By KCBS All News 106.9FM and 740AM

It turns out that mask-wearing simultaneously serves as self-care and altruism.

While health officials have been urging us to wear masks to protect those around us, research out of the University of California, San Francisco suggests masks insulate the wearer from the coronavirus more than previously thought.

Think of it like an umbrella that can keep you from getting too wet, as this new study suggests masks can keep you from getting too sick. The paper - to be published in the Journal of General Internal Medicine - concludes masks limit the wearer's exposure to the virus and with less exposure, the less sick you're going to get. 

Dr. Monica Gandhi is a UCSF infectious disease expert and one of the authors of the study, which, in part, looked at data from Japan's Diamond Princess cruise ship where more than 80% of those on board came down with symptoms. That was before masking was recommended, but on a different cruise where people did cover their faces, the number of symptomatic cases was short of 20%.

"UC guidelines say you have to be 15 minutes around someone, that’s their definition of 'contact,'" she told KCBS Radio. "But what we don’t know is how long you can be around someone with a mask."

Now the question is - just how immune are those masked cases? 

"Could we get away with, you don’t have symptoms and yet you’ve gotten yourself immune by getting infected without symptoms? That is the next big question," she said. "That would be amazing because then we’ll slow down the spread of the virus from herd immunity itself."

This comes as Contra Costa County Supervisors on Tuesday are expected to consider imposing hundreds of dollars in fines on people who don't wear masks.

Several North Bay counties already do.