Will Mask Mandates Help Stop Omicron Spread? What We Know

A clerk checks out a customer at a grocery store.
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  • Public health experts are pushing for statewide mask policies to slow the spread of the Omicron and Delta variants.
  • Only nine states have enacted statewide mask policies.
  • Data suggests that Omicron may be more likely to reinfect people than Delta. Omicron may also overcome some of the protection offered by the COVID-19 vaccines.

As the Omicron variant picks up speed in the United States, public health experts in some states are calling for new mask policies to soften the blow of a winter surge — which will involve both Omicron and Delta variants of the coronavirus.

They point out that these kinds of mitigation measures can slow the transmission of the coronavirus — especially when implemented early — and lessen the impact of the surge on hospitals, schools, the economy, and our lives.

“Mask policies are actually the opposite of lockdowns or closures, because they allow us to share spaces more safely,” said Julia Raifman, ScD, an assistant professor of public health at Boston University.

The coronavirus spreads through the air, so broad use of face masks can reduce the amount of virus in shared air. Masks are especially helpful in indoor public spaces with poor ventilation.

Masks also work against Omicron, because it spreads in the same way as previous variants of the coronavirus.

In many parts of the country, coronavirus cases are rising sharply.

Compared with 2 weeks ago, the 7-day daily average of coronavirus cases has increased by more than 200 percent in Florida and Washington, D.C., and by more than 300 percent in Hawaii and more than 600 percent in Puerto Rico.

In California, the 7-day daily average of cases in Los Angeles County has increased 55 percent over 2 weeks ago, and by 77 percent in San Francisco County.

As of Dec. 11, Omicron makes up an estimated 3 percent of cases, a sharp rise from a week earlier, according to the Centers for Disease Control and Prevention (CDC).

While Omicron is gaining speed in the United States, the Delta variant is still helping drive the surge in cases as the holidays approach.

Some places, though, are reporting higher numbers of Omicron cases. At Houston Methodist Hospital, 82 percent of symptomatic infections are due to Omicron, Dr. S. Wesley Long, an associate professor of pathology and genomic medicine at Houston Methodist, wrote Dec. 19 on Twitter.

In spite of the rise in coronavirus cases in many parts of the country, only nine states have enacted statewide mask policies, according to the Kaiser Family Foundation.

Even some states with sharp increases in COVID-19 hospitalizations — like Rhode Island, New Jersey, and North Carolina — don’t have statewide mask policies.

And Connecticut, which has the sharpest rise in hospitalizations over the last 2 weeks, has a mask policy that applies only to unvaccinated people.

This conflicts with the CDC’s guidance, which recommends that everyone in areas with high coronavirus transmission wear a mask in indoor public settings.

Currently, that’s most of the country, according to CDC data.

“I don’t understand why policymakers are putting in place mandates that fall short of [CDC recommendations] at this time, especially in light of the emerging evidence on Omicron,” said Anne Sosin, MPH, a policy fellow at Dartmouth College’s Nelson A. Rockefeller Center for Public Policy and the Social Sciences.

Omicron increased need for mask policies

When the COVID-19 vaccines first came out, scientists thought that fully vaccinated people had a low risk of contracting the coronavirus and transmitting it to others.

But that changed with the Delta variant.

Although vaccinated people are less likely than unvaccinated people to contract the Delta variant, if they do, they can transmit the virus just as easily, although for a shorter period.

Omicron, which is spreading more quickly than Delta, has shifted things even more. 

Data suggests that Omicron may be more likely to reinfect people than Delta. Omicron may also overcome some of the protection offered by COVID-19 vaccines.

Experts think that full vaccination will still protect against severe illness in the face of Omicron, with a booster providing additional protection.

But Omicron is likely to infect more people who are vaccinated or had a prior infection, compared with Delta.

This will sharply increase community transmission of the coronavirus over the coming weeks, which is why experts are recommending broad mask policies.

“With Omicron likely having a higher rate of escaping previous immunity and also a very high transmissibility in general, the pandemic changes,” said Julie Swann, PhD, a professor in the Fitts Department of Industrial and Systems Engineering at North Carolina State University.

“So we need to be able to change our behaviors and policies correspondingly,” she said.

Mask polices slow community transmission

Swann said research shows that face masks — worn properly — can reduce coronavirus transmission, and that mask policies can work.

In a Sept. 15 preprint shared on medRxiv, Swann and her colleagues modeled what would happen if K–12 schools in North Carolina implemented mask policies at the start of the school year.

They found mask policies in fully open schools would reduce additional infections in the community by 23 to 36 percent, depending on the quality of the mask.

Swann also pointed to what happened at the start of the school year in states without school mask policies, like Texas, Florida, Georgia, and North Carolina.

“When schools opened without mask policies in place, it very quickly led to an overwhelming number of infections,” she said. “Many schools then changed their policies and put mask mandates back in place, and infections dropped quite a lot.”

Researchers at the University of Pittsburgh and Carnegie Mellon University have also been tracking what happens to coronavirus cases as states enact and drop mask policies.

Their data shows that when Louisiana implemented a mask policy on Aug. 4, 2021, cases started to decrease within 14 days. The duration of the state’s peak was also shorter than that in Mississippi, which has a similar vaccination rate.

Similar trends were seen in states with higher vaccination rates.

Researchers don’t have data on how well people in the states followed the mask policy. 

However, another study estimated that even if just half of the population regularly wears a medical-grade mask or high quality cloth mask, it can have a big impact on the spread of the virus.

Those researchers’ estimates were made based on data from early in the pandemic, so slowing the spread of Delta and Omicron may require higher mask use in a community.

Other research compared mask policies at the county level in Kansas.

Researchers found that coronavirus cases were more than two times higher in counties without a mask policy than those with a mask policy. Hospitalizations were also 1.4 times higher in no-mask counties.

Masks one of many mitigation measures

How well mask policies work vary from state to state or county to county, depending on a number of factors.

“In some places, there’s really effective implementation, so we get very high levels of compliance with masking,” said Sosin.

“But masks only work when they’re worn. So the effectiveness of a policy depends as much on its design as the degree of implementation,” she said.

Sosin added that political leaders also need to clearly communicate the benefits of wearing masks for the individual and the community.

“If [political leaders] repeatedly tell people that masks don’t work well, that’s going to undermine their usage at community level,” said Sosin.

In addition, mask policies need to be used alongside vaccination, testing, better indoor ventilation, and other public health measures.

This can reduce community transmission, which will also decrease how many people are showing up at the hospital at the same time with COVID-19.

This is good for everyone in the community.

“When hospitals are overwhelmed, mortality rates increase not just for COVID, but for car wrecks and heart attacks and everything else,” said Swann. “So putting in place a mask mandate can slow things down and keep the hospitalizations more manageable.”

Although full vaccination and boosting provides the strongest protection against severe COVID-19, it can take a long time to vaccinate entire communities. 

Even 1 year after the rollout of the COVID-19 vaccines began, about 15 percent of U.S. adults have not received a single dose, according to the CDC. The unvaccinated rate is higher in certain communities.

In contrast, a mask starts working as soon as you put it on.

“Mask policies begin reducing transmission immediately,” said Raifman. “And the reduction in transmission increases over time, because each case [that is] averted reduces onward transmission to other people.”

Not everyone agrees that mask mandates will have a big impact on the course of the winter surge.

Dr. Monica Gandhi, an infectious diseases specialist with the University of California, San Francisco, said some data suggests that vaccination rates had a bigger impact on Delta transmission in California than mask mandates and other restrictions.

“I don’t think a return to general mask mandates — surgical or cloth masks — will make a difference, and we probably can’t ask the whole population to use N95 masks after [being vaccinated],” she said.

However, because a mask protects the person who is wearing it, Gandhi said people who are at higher risk from COVID-19 can choose to wear a high quality mask — N95, KN95, or KF94 — or double masking if one isn’t available.

This also applies to other people who want to lower their risk of infection in indoor public spaces.

“The public should be informed of more effective masking choices — especially if [they are] immunocompromised or vulnerable,” she said. “And those masks should be recommended and not mandated, given where we are in the pandemic.”

Public support for masks is strong

Since the CDC first recommended face masks, there has been an online disinformation campaign against masks, along with a handful of high profile editorials calling for mask use to be dropped.

But Raifman said support for mask policies remains high.

When the CDC ended the mask policy guidance in May, most epidemiologists thought we still needed to be wearing masks for 6 months or longer, Raifman said.

“And that was before the Delta variant came along,” she said.

Even a large share of the public is in favor of masks. A Morning Consult poll in July found that 72 percent of people were in favor of mask policies in public spaces. This was before Omicron.

“Seventy-two percent of people want mask policies because they know they protect themselves,” said Raifman. “And they know that they protect each other and they protect their community.”

She doesn’t think we will need to wear face masks forever, but she is pushing for mask policies to be turned on and off based on real-world data.

Data-driven mask policies can help reduce coronavirus transmission, preserve healthcare capacity, keep businesses and schools open, and protect the most vulnerable people in the community.

“We can mask together for a few weeks to help avoid more children losing their parents forever,” Raifman said.

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