San Diego researchers say double masking could slow the spread of COVID-19

With new and more infectious coronavirus strains on the rise, some San Diego public health experts say it’s time to double mask when you’re out and about.

Wearing two masks could lower your odds of getting or spreading COVID-19 while at work, on an airplane or grocery shopping, researchers say, provided that those masks fit snugly. And given the glacial pace of the COVID-19 vaccine rollout, a mask remains one of the best ways to protect yourself against the coronavirus.

The Centers for Disease Control and Prevention hasn’t issued an official recommendation for or against double masking. Neither has the county. But the nation’s top infectious disease expert, Dr. Anthony Fauci, says the idea makes common sense. And San Diego State University epidemiologist Corinne McDaniels-Davidson, who leads local contact tracing efforts in underserved neighborhoods, says community health workers have been double masking since August.

She thinks it’s time for the rest of us to do the same.

“You go to the grocery store, you’re sharing air with people who aren’t in your household. It’s the ideal time to be doubling up on masking,” McDaniels-Davidson said. “Public health measures are going to become even more critical to pair with the vaccine.”

It may seem like odd advice at a time when coronavirus cases and hospitalizations are leveling off. But things can change quickly. On Tuesday, UC San Diego infectious disease modeler Natasha Martin warned the county Board of Supervisors that a faster-spreading coronavirus variant first spotted in the U.K. could lead to fresh surges in cases and hospitalizations in the next few months.

Vaccination alone won’t avoid that scenario, as it’ll take at least until the summer to inoculate enough people to substantially slow the spread of the coronavirus. But basic public health measures such as social distancing, washing your hands and wearing a mask can have an immediate impact.

The key is to use these strategies together, says UC San Diego infectious disease specialist Dr. Robert “Chip” Schooley, who is quick to point out that researchers don’t know exactly how much more protective two masks are than one.

“You might not get as much benefit out of that as you think,” Schooley said. “It would be a bad message to say, ‘Well, slap on another mask and don’t worry so much because you’re doubly safe.’”

If you do want to double mask, McDaniels-Davidson says you can wear two of the same mask, or a higher grade mask (such as an N95 or KN95) on the inside with a surgical or cloth mask on top. One bonus is that the inner mask will have less exposure to the elements and last a bit longer.

Both Schooley and McDaniels-Davidson agree that the key is to fit any mask (or masks) securely over your mouth and nose — otherwise, a second mask won’t do any good.

“I’d rather someone wear a really well-fitting mask than two masks that don’t fit well,” McDaniels-Davidson said.

For additional information on masking, visit the CDC’s website.