Masks and COVID-19 Variants

On November 26, 2021, the World Health Organization announced Omicron as the COVID-19 variant of concern.

Omicron is not only more transmissible than other previously identified 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, told Health.

Despite Omicron's rapid spread, the good news is that COVID-19 strategies like vaccination, masking, and social distancing could slow its transmission. Some states—like California and New York—reinstated masking mandates at that time.

Here's what Health learned about how well masks protect against Omicron.

Masks and the 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 said.

However, masks are an imperfect barrier, meaning some virus particles still slip through.

"Omicron produces more virus, even than Delta," Dr. Schaffner said, pointing out that some research 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," Dr. Schaffner explained.

But that doesn't mean masks are worthless against Omicron. Instead, masking is just one piece of the puzzle regarding 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 said. "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," Dr. Schaffner explained.

The most robust slice of cheese would be the vaccine. Vaccines remain the best public health measure to protect people from COVID-19, according to the CDC.

And 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, told Health.

As Dr. Schaffner noted, "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. You can follow transmission data by using the organization's COVID-19 case map.

How To Wear a Mask To Protect Against Omicron

When it comes to masking, Dr. Schaffner said 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 from leaking out of the top
• Should not have exhalation valves or vents, which allow virus particles to escape.

Surgical masks and good multi-layer cloth masks will fit the CDC guidelines and are also inexpensive, Dr. Schaffner said. If you want even more protection, Dr. Danielle Zerr recommended that you place a cloth mask over a disposable mask so that it fits snugger. You can also opt for KN95s, 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 said. "Even breathing in and out can contaminate the air around us up to three feet or even a little further," Dr. Schaffner explained.