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Do people vaccinated against COVID-19 ever need to wear masks?

Minnesota’s mask mandate ended more than a month ago, but that doesn’t mean everyone has dropped their masks.

Is there any scientific reason to keep wearing masks?
Is there any scientific reason to keep wearing masks?
REUTERS/Jeenah Moon

It’s been more than a month since Minnesota’s indoor mask mandate ended.

Masks are no longer required by the state in grocery stores, restaurants, theaters or bars. They are still recommended for people not vaccinated against COVID-19 and even for the vaccinated in some settings, like hospitals and child care.

In some parts of the state, you wouldn’t know the mask mandate had ended, as people — including fully vaccinated people — continue to wear masks, perhaps more as a social measure than a disease preventing one.

But for the fully vaccinated, is there any scientific reason to keep wearing masks? Experts say if you consider all the factors at play in virus transmission, the answer might not be a hard “yes” or a hard “no.”

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The evidence

First off, the Centers for Disease Control and Prevention still recommends people who aren’t vaccinated keep wearing masks in public. Research has found masks effective in slowing the transmission of COVID-19 — offering some protection to the wearer of the mask, but also protecting the people around them by preventing at least some viral particles from being airborne and breathed in by others.

But when it comes to the vaccinated, each of the three vaccines approved for use in the U.S. has been found to be highly effective in preventing people from getting sick from COVID-19.

That’s been proven not just in clinical trials but in real life, as Minnesota’s COVID-19 case numbers have dropped since the introduction of the vaccines in December. And it means that if you are vaccinated, it’s really quite unlikely you will get sick from COVID-19.

It’s also unlikely that you’ll give COVID-19 if you’re fully vaccinated. Early on in the vaccine rollout, the science on this wasn’t as clear – we only knew that the vaccines prevented people from getting sick. But with so many people vaccinated now, a clearer picture of the vaccines’ efficacy is emerging. Research finds they’re good at not only preventing sickness but also transmission, said Dr. Beth Thielen, an infectious disease physician with the University of Minnesota Medical School and M Health Fairview.

At least for now. The verdict is less clear in terms of how long the vaccines’ protection will last as well as whether they’ll be able to thwart all variants effectively.

But even when it comes to the strain of COVID-19 that was predominant last year — before the more infectious variants — the vaccines are not 100 percent effective, said Kris Ehresmann, the infectious disease director at the Minnesota Department of Health. As of last week, Minnesota had seen fewer than 3,000 breakthrough cases (representing less than 0.1 percent of vaccinated people), which refer to cases that have developed in people who have been fully vaccinated. Usually, these cases aren’t severe, but in rare cases, they are.

It’s also not a bad idea to consider the vaccination status of the community when deciding whether to wear a mask, Ehresmann said.

While more than 50 percent of Minnesotans over the age of 16 statewide have been fully vaccinated, that number varies considerably depending on what part of the state you’re in. In parts of Central Minnesota, it’s far less, which means any given person at the store in some of these counties is less likely to have been vaccinated and more likely to transmit COVID-19.

For a fully vaccinated person, the risk is low, but not totally nonexistent.

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“This is sort of a personal comfort choice issue,” Thielen said. “I will say for myself, I’m fully vaccinated, I have stopped wearing a mask and in grocery stores and those sorts of places.”

While the vaccines work well on the whole, there’s a certain percent of the population whose bodies don’t mount enough of an immune response to the vaccines to give them full protection, whether that’s because of ongoing chemotherapy, organ transplant or other conditions, Thielen said.

“That is a real legitimate area of concern – that people would still want to wear masks to protect themselves or household contacts that they might be putting at risk,” for COVID-19 and for other diseases, she said.

Ehresmann said that because some people who are immunocompromised don’t have the full protection of a vaccine, it’s important that even where masks are no longer required, people’s wishes to wear a mask is respected.

Collateral benefits

It’s important to remember, too, that masks have collateral benefits beyond slowing the spread of COVID-19, Thielen said.

Right now, the U.S. is seeing an unseasonable wave of RSV, or respiratory syncytial virus, in small children, Thielen said. Usually a winter virus, this common respiratory disease is often mild but sometimes serious, causing lung inflammation and pneumonia. Keeping up the mask-wearing can help slow the spread of RSV and other respiratory diseases.

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“It’s not just protecting against COVID, or preventing transmission of COVID, it’s protecting against transmission of all these other things, which we had a nice little break from while everybody’s been distancing,” Thielen said.

Thielen also said that, pandemic or not, masks are a good choice in environments where there’s lots of potential for disease spread or where people may be immunocompromised, like clinics and hospitals.

“When I’m at work, I am worried about not just myself, but that I’m around a lot of immunocompromised people and I don’t want to be the one that spreads what could be a potentially fatal infection to one of my patients,” she said. A lasting cultural change of wearing masks more in settings like this and other tight quarters, especially during the winter when virus transmission is high, could help keep everyone healthier, she said.

And even as many tire of the pandemic the masks signify, Ehresmann said it’s important to remember that masks don’t hurt anyone.

“I’ve always said it’s never wrong to wear a mask,” Ehresmann said. “People who are wearing masks have added up all the risks and the benefits and said, ‘Well, OK, I think I’m going to still choose to wear a mask.’”