When the coronavirus disease (COVID-19) pandemic took hold in 2020, questions about the effectiveness of wearing masks to prevent the spread of the virus rose as well. Three and a half years later, what does the science say?
Dr. John LaPook, chief medical correspondent for CBS News, posed that question to Lindsay Marr, a Virginia Tech professor who specializes in aerosol science, in an interview on 60 Minutes.
Ma said masks are “very helpful in reducing the chance of a person getting infected with coronavirus because they reduce the amount of virus they inhale from the air around them.”
No mask is 100% effective. For example, N95 is so named because it is effective at blocking airborne particles by at least 95 percent when used properly. But even if the masks were 80% effective, Marr said, they would still provide meaningful protection.
“This greatly reduces my chances of getting infected,” Marr said.
Ma said studies have shown that high-quality masks can block particles the same size as those that carry the coronavirus. Masks act as filters, not sieves, Ma explained. Virus particles have to weave around layers of fibers, where they can collide with and become trapped.
Marr compared it to running through a forest of trees. Walking slowly makes it easier to navigate your surroundings. However, if you drive through the forest at high speed, you are more likely to hit a tree.
“Masks, even cloth masks, do something,” she said.
Can a contaminated face mask cause an infection?
Early in the pandemic, some guidance from medical experts suggested that wearing masks could actually cause infection. People can come across a contaminated mask and touch their eyes, nose, or mouth. However, subsequent research has shown that fears to be misplaced.
“There was no evidence that that would actually happen,” Marr said.
Ma said her team aerosolized the coronavirus and inhaled the virus through a mask to see how much virus survived on the mask. The study reported that virus particles remained in some cloth masks, but not in N95 masks or surgical masks.
Ma’s team also tested how many virus particles transferred to the artificial skin by exposing the masks to artificial skin. Infectious viruses are not transmitted.
“I hope this study shows that we don’t need to worry as much as we’ve been told,” Marr said.
The video above was edited by Sarah Shafer Prediger.