When should you wear a mask to protect against the Delta variant? (video)

A UC Davis infectious disease expert weighs in on the evolving mask guidance

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(SACRAMENTO) — The guidance about masking has changed significantly this week, as the highly contagious COVID-19 Delta variant spreads rapidly throughout the country and Sacramento County.

The Centers for Disease Control and Prevention recommended that vaccinated people should mask up indoors in areas of “substantial or high transmission” (unvaccinated people were already asked to wear masks). The California Department of Public Health quickly followed suit, recommending universal masking for everyone. And the Sacramento County Department of Public Health issued new guidance, requiring all residents to wear masks in indoor public settings due to a COVID-19 case rate that has “drastically risen.”

Learn more about the Delta variant.

Stuart Cohen, Chief of the UC Davis Health Division of Infectious Diseases, explains why masking is important, what type of mask you should consider, and when you should be wearing one.

What are the latest guidelines on masking?

The Centers for Disease Control and Prevention and the California Department of Public Health basically said that when there are high levels of COVID-19 transmission within your area, that people should be masked indoors, including everybody who is vaccinated.

Why now?

We’ve noticed that the Delta variant is about 1,000 times higher in amount of virus in people’s nose than the initial variant that we saw back in February and March of 2020, so that means there is a lot more virus being spread. That also means that it is much more easily transmitted. If everybody had been vaccinated, this may have been totally averted. Also, Delta isn’t going to be the last variant, and that’s in large part on the unvaccinated community.

Given these latest guidelines, what’s your best advice?

“This is a safe vaccine, and it works. We felt like we were close to the end and now we’re right back in the soup again. It’s maddening.”

— Stuart Cohen, chief,
Division of Infectious Diseases

I never stopped wearing a mask at a grocery store because I’ve never trusted that everybody not masked is truly vaccinated, so I believe that if you go grocery shopping, you’ve got to mask up. If you’re outdoors you probably can still get away without masking. But anything indoors, where you’re not within your little bubble of people you know are vaccinated and part of your family, you have to mask up.

Can you elaborate on masking outdoors?

There’s a lot more air exchange, people are not quote as clustered together. I think the inoculum of the virus that gets close to your body becomes much smaller in open space. That’s why transmission rates even from the beginning have always been significantly lower outdoors than they are indoors.

Please remind us, why are masks are so important?

Masks work in two ways: For the person who is infected, the mask filters some of the virus coming out of their mouth or their nose, so it limits the amount of virus that comes through. For the person on the other end who’s wearing a mask, who’s not infected, then whatever viruses get to that person has to go through his or her mask. That also decreases the amount of virus it comes through.

Given the severity of the Delta variant, what sort of masks should we be wearing?

Unless you are going to be in very intense circumstances, wearing a surgical mask should be more than adequate, or wearing a good cloth mask that fits well, particularly cloth masks that actually have filters on the inside of them.

How can children be protected from the Delta variant?

Since a vaccine is not yet available for kids 11 and under, they have to be masking, and should try to limit their close contact with groups of people.

What else should we know?

If anybody ever wants this pandemic to end, they’ve got to get vaccinated. “This is a safe vaccine, and it works. We felt like we were close to the end and now we’re right back in the soup again. It’s maddening.”

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