Do Masks Protect Against the Omicron COVID-19 Variant? Yes, But They May Be Less Effective—Here's Why

Infectious disease experts say that Omicron may be better at slipping through masks, but face coverings are still an important pandemic tool.

On November 26, the World Health Organization announced Omicron as the latest COVID-19 variant of concern. Since then, the strain has outcompeted Delta to become the dominant strain of COVID-19 in the US, making up 95.4% of all infections in the country, as of January 1, according to the Centers for Disease Control and Prevention.

Omicron is not only more transmissible than other strains of the virus, but it also seems to better evade immunity from vaccines and prior infections, William Schaffner, MD, a professor of health policy and infectious diseases at the Vanderbilt University School of Medicine, tells Health.

Despite Omicron's rapid spread, the good news is that current COVID-19 strategies like vaccination, masking, and social distancing can slow its transmission. In fact, some states—like California and New York—have reinstated masking mandates.

Here's what we know so far about how well masks protect against Omicron and whether more people should start wearing them, again.

Do masks protect against Omicron variant?

Masks continue to be effective at reducing the risk of contracting or spreading COVID-19, including the Omicron variant, according to the CDC. That's because masks are not variant specific. Instead, they act as a barrier, trapping and filtering out virus particles from the air we breathe, Dr. Schaffner says.

However, masks are an imperfect barrier, meaning some virus particles still slip through. The likelihood some particles escape is probably even greater when it comes to the Omicron variant.

"Omicron produces more virus, even than Delta," Dr. Schaffner says, pointing out that some research has found the variant infects and multiplies 70 times faster than Delta. "So, the masks' capacity to interrupt or reduce transmission back and forth is likewise reduced."

But that doesn't mean masks are worthless against Omicron. Rather, masking is just one piece of the puzzle when it comes to protecting you and your community from the variant.

"We have to think of these interventions as though they were a series of Swiss cheese slices," Dr. Schaffner says. "Each slice produces a barrier, but it has holes in it! It's not perfect. So, you can't rely on just one intervention to protect us. We have to do a whole series of things."

Of course, the most robust slice of cheese would be the vaccine. In fact, "vaccines remain the best public health measure to protect people from COVID-19," according to the CDC. Although even those who are vaccinated (or have their booster) should still start, or continue, wearing a mask, especially in crowded indoor situations Danielle Zerr, MD, medical director of infection prevention at Seattle Children's Hospital, tells Health.

As Dr. Schaffner notes, "Omicron can even infect people who are fully vaccinated and boosted, so we don't want to be spreaders to others, even if breakthrough infections are mild."

This echoes CDC guidelines which state people should wear masks indoors in areas where community transmission of COVID-19 is high or substantial—almost the entirety of the country per the organization's COVID-19 case map.

How to wear a mask to protect against Omicron

When it comes to masking, Dr. Schaffner says any barrier is better than no barrier. However, for masks to be most effective at protecting against COVID-19, they should meet certain criteria. According to the CDC, your mask should:

  • Have two or more layers of washable, breathable fabric
  • Fit snuggly against the sides of your face so you don't have gaps
  • Have a nose wire to prevent air leaking out of the top
  • And should not have exhalation valves or vents, which allow virus particles to escape

Surgical masks and good multi-layer cloth masks will fit the above guidelines and are also inexpensive, Dr. Schaffner says. If you want even more protection, Dr. Zerr recommends you place a cloth mask over a disposable mask so that it fits snugger. You can also opt for KN95s, which are designed to hug the face.

Most importantly, your mask needs to cover both your mouth and nose. "We can shed the virus, and thus spread the virus, just by breathing through your nose," Dr. Schaffner says. "Even breathing in and out can contaminate the air around us up to three feet or even a little further."

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