Study comparing surgical masks to N95s stirs controversy

Surgical masks can ward off COVID-19 just as well as N95s for healthcare workers exposed to patients infected with that virus, a study in the Annals of Internal Medicine suggests.

To report that this message has not been well received would be understatement.

Nonetheless, the lead author of the study told Fierce Healthcare that he stands by his work, despite the intense backlash it has generated.

“Within the pandemic, there are several topics that seem to be associated with controversy,” Mark Loeb, M.D., a professor of pathology and molecular medicine at Canada's McMaster University, told Fierce Healthcare. “Including the origin of SARS-CoV-2. Including whether children should be in school or outside of school and whether they should wear masks. And the whole discussion around masks tends to be quite controversial. So, it’s not surprising that there are polarized reactions to the findings of the study.”

That’s certainly the case in an article in CIDRAP News, a publication from the Center for Infectious Disease Research and Policy at the University of Minnesota. Many of the experts quoted complained about the study’s methodology and that the main message, if followed, would put healthcare workers in danger not only from COVID-19, but from other pathogens that might be encountered in a hospital setting.

Michael Osterholm, Ph.D., the center's director, said that the case that surgical masks provide much less protection against COVID-19 than N95s should be closed by this point.

He told CIDRAP News that “we just don’t need another poorly designed and conducted study on this.” He added: “I’m convinced that someday people are going to look back on this and ask, ‘How could they have known what they knew about this and not done more to protect us’?” (One of the major manufacturers of N95s, 3M, is listed as an underwriter on the CIDRAP website.)

But what do frontline workers in healthcare settings think?

Linda Dickey is the president of the Association for Professionals in Infection Control and Epidemiology, an organization that represents about 15,000 infection prevention experts and other healthcare professionals worldwide.

“I don’t want to disparage the manufacturers of N95s who have provided us with what they have,” Dickey told Fierce Healthcare. “But I don’t think that we ever really envisioned people having to wear these masks for eight, ten, 12 hours a day. And that’s just unfortunate for healthcare workers who work in operating rooms and emergency departments and ICUs. Even in medical-surgical units and long-term care. They’ve been wearing these things literally for hours, and it’s uncomfortable, to put it mildly.”

Dickey said that she had not read Loeb’s study in the Annals of Internal Medicine, but she did read the CIDRAP News article and said that the points raised about the methodology “were good ones” that, if proven true, would make her wonder about the accuracy of the results.

Dickey said she has yet to see a well-designed study comparing different types of masks that would resonate with healthcare workers on the frontlines.

“We have seen a mixture of masks being used worldwide, and I don’t think that we fully know. Even though it’s clear that this was not just large droplets, that there was some degree of aerosolization involved in [COVID-19] transmission. I think we still have a lot to learn about what exact type of mask would be helpful.”

In September, APIC urged its members to disregard the CDC’s advice when the federal agency loosened masking guidelines for healthcare workers. Among other reasons, APIC thought it was a bad idea to do so on the cusp of flu season and predicted that the CDC might have to reverse course and go back to the stricter guidelines.

“Having a policy that changes back and forth is confusing to healthcare personnel and erodes trust,” APIC said in a statement. “Furthermore, rising COVID cases could lead to healthcare worker shortages, a situation we all want to avoid.”

Dickey said that “our statement really didn’t come out about the type of mask as much as it was just about masking, keeping healthcare workers safe.”

She hopes that the National Institute for Occupational Safety and Health (NIOSH)—whose stamp of approval ensures that a mask should be able to protect healthcare workers—eventually spearheads the creation of a comfortable mask that doesn’t require a lot of fit testing and can be universally worn.

“It would be one kind of mask that we would wear, whether it’s large droplets or aerosols,” said Dickey. “That would be the goal. But right now, I think that we still have a lot to learn about what kind of mask protection really was necessary for COVID.”

For the study in the Annals of Internal Medicine, researchers with McMaster University in Canada collected data from more than 1,000 workers at 29 hospitals in Canada, Israel, Pakistan and Egypt who directly cared for infected patients from May 4, 2020, to March 29, 2022. Of the 497 healthcare workers who wore a surgical mask, 52 became infected. Of the 507 who wore N95s, 47 were infected—not statistically significant.

Loeb told Fierce Healthcare that “it’s important to note that the use of the mask was universal. So, in other words, when the healthcare provider entered the trial, they had to wear either the N95s, or the medical masks from the time they entered the hospital to when they left. We measured adherence to the mask by self-reporting, as well as via external monitoring at selected sites. And overall, there was a 1.19% increase in the risk of COVID infection in participants assigned to medical masks compared to N95 respirators. And this is what’s known as the point estimate. And that’s really the result that’s closest to the true effect.”

Elastomeric Respirator
An elastometric respirator (Getty Images)

Lisa Brosseau, a nationally known expert on respiratory protection and infectious disease, has been skeptical about the utility of cloth masks throughout the pandemic. She told CIDRAP News that a better masking option exists other than surgical masks or N95s.

“Elastomeric respirators with replaceable filters, which can be cleaned and reused many, many times, would have been a better long-term solution than disposable FFRs,” Brosseau told CIDRAP News. “If every HCW had been given a fit-tested elastomeric respirator in early 2020, many HCW and patient infections would have been prevented. And HCWs could still be wearing that same elastomeric respirator today.”

Dickey disagrees.

“It’s very off-putting to have to wear that as a healthcare worker, even though it’s protective,” she said, reiterating that APIC’s primary concern continues to be patient care and healthcare worker safety.

"However, having said that, the thing looks incredibly scary,” says Dickey. "You know, like, for pediatric patients, particularly, and even some adults. It’s a difficult piece of gear to use really effectively in some healthcare settings. Is it protective? Yes. But is it the best we can do? I think science can move us forward a little bit.”

Loeb noted that public policy about masking throughout the pandemic and in many countries has often been confusing.

“What prompted us to undertake the study in the first place was that policy was very different around the world in terms of use of either medical masks or N95 respirators for healthcare workers dealing with COVID patients,” Loeb said. “For example, the World Health Organization, originally in the pandemic recommended medical masks. The Centers for Disease Control and Prevention in the U.S. recommended N95 respirators. As the pandemic evolved, the World Health Organization then recommended either medical masks or respirators.”

Loeb said that he wasn’t “terribly surprised” by the findings. “It’s a pragmatic trial. It’s evidence that occurs in real life. I would have been surprised if the medical masks were superior to the N95 respirators. I wouldn’t have been surprised if the N95 respirators were superior. But in effect, they weren’t, and it was just a minimal difference between the two.”