Without other pandemic precautions, hospital mask rules didn’t stop COVID spread, study finds

A woman wears a mask along with medical personnel at a hospital as her baby daughter is examined.
Latoya Hawkins wears a mask as her 4-month-old daughter is examined at MLK Community Hospital in January.
(Francine Orr / Los Angeles Times)

In a world moving on from the COVID-19 pandemic, hospitals and medical offices have been the last bastions of mandatory masking. But new research finds that in communities where pandemic precautions have been largely abandoned, mask mandates in healthcare settings do little to prevent coronavirus infections among patients.

The findings, presented on Thursday at the European Congress of Clinical Microbiology & Infectious Diseases in Copenhagen, suggest that hospitals, nursing homes and clinics could adopt “mask optional” policies without putting their patients at increased risk.

The study’s findings come almost a year after most European governments decided to let the virus spread unimpeded among their highly vaccinated populations. But with some of the last masking requirements now being dismantled in the United States, many here continue to debate the wisdom of declaring an end to the public health emergency.


The U.S. Centers for Disease Control and Prevention continue to recommend indoor masking for all in communities where new infections, hospitalizations and local hospital capacity combine to push COVID-19 into a “high” risk level, and for people who may become severely ill with COVID-19 if they live in communities where the risk level is “medium.” But for the 96% of counties where the risk is deemed “low,” masks are neither recommended nor discouraged.

This week, California health officials lifted the general masking order for healthcare settings throughout the state while allowing individual hospitals, doctor’s offices and other facilities to set their own requirements.

Los Angeles and San Francisco counties have lifted their masking orders for patients and visitors. But under new local orders, doctors, nurses and other employees will be required to wear masks while providing patient care or working in patient areas at hospitals, clinics, skilled nursing facilities, dialysis centers and the like.

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L.A. County rules also require continued masking by janitors, security officers, secretaries and volunteers who work in patient-care areas, as well as by firefighters, emergency medical technicians and police officers who enter such places.

The British authors of the new study appeared to question the value of such broad masking policies, both in the absence of masking outside of hospital walls and in light of evidence that the pandemic virus has become less likely to kill than it was three years ago.

“A low-tech, low-cost intervention without well-established benefit was reasonable in the context of the early pandemic,” wrote the authors of the new study, referring to the widespread use of face-coverings. “However, with a reduction in the severity of COVID-19 disease, in later variants, the risk-benefit balance becomes more questionable.”


Dr. Aodhan Breathnach, an infectious disease physician with the National Health Service Foundation Trust and one of the study’s authors, said many hospitals “have retained masking at significant financial and environmental cost and despite the substantial barrier to communication.” He expressed hope that the study’s findings “can help inform a rational and proportionate mask policy in health services.”

In the United Kingdom as in the United States, continuing mask mandates “became politicized,” Breathnach said. “Rather than people just flocking to their political tribe, we said, ‘Let’s see how much they actually work.’ The data were just sitting there.”

Breathnach and his colleagues in the U.K.’s National Health Service set out to test whether changes in masking policies for hospital visitors and staff resulted in changed infection rates among patients on the wards of St. George’s Hospital in southwest London. They focused on a 40-week period that began in December 2021, when the Omicron variant had established itself as the dominant coronavirus strain.

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In the first 26 weeks, masking was required of all hospital visitors and healthcare workers. The researchers captured rates of infection among patients upon admission and rates of hospital-acquired coronavirus infections during that time. In-hospital infection rates were much lower that those detected at admission, but the two tracked up and down largely in tandem.

On June 2, 2022, masking became optional for healthcare workers and visitors in most wards of St. George’s. However, on cancer wards, in dialysis suites and intensive care units, and at medical admissions, the mask mandate stayed in place. That allowed those areas of the hospital to serve as the study’s control group.

For the next 14 weeks, researchers found that patients admitted to wards where masks were optional were no more likely to become infected inside the hospital than were patients in units where masking remained mandatory.


For both sets of patients, the relationship between infections at admission and hospital-acquired infections followed the patterns established in the first 26 weeks of the study. That held up even in July 2022, when London experienced a huge Omicron surge: Infections among newly admitted patients rose dramatically, and throughout the hospital, rates of in-hospital infection continued their customary pattern of rising less dramatically.

Breathnach said the stability of the group’s findings, even as a surge swept through London, gave them confidence that universal masking in hospitals had become hard to defend. Still, he said he understands why demands for continued masking would be the final fall-back for many people.

“There’s a certain psychological aspect to masking: it’s the most visible control measure, and you feel you have control over it. And other public health measures, like social distancing, are so much harder to do,” he said. But when virtually all other strictures have gone by the boards and only hospital workers are wearing masks, their face coverings barely make a difference.

“They have a marginal ability to protect against a disease that’s increasingly less severe,” Breathnach said.

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At the Copenhagen meeting of microbiologists, experts continued to debate how much less severe COVID-19 has become. Another study presented Thursday assessed the virus’s power in the context of another widespread respiratory disease, influenza.

While the Omicron variant appears to have rendered the coronavirus less virulent, research from Israel affirms that it remains deadlier than flu.


Scientists compared the characteristics and outcomes of 167 Israeli hospital patients admitted with COVID-19 between December 2021 and January 2022 to those of 221 admitted with a flu infection during the same period.

The COVID-19 patients, half of whom were older than 71, were more likely to require oxygen support, to be put on a ventilator and to die than were the slightly younger patients with influenza. Of the 167 patients hospitalized for COVID-19, 26% died within 30 days of admission. By contrast, 9% of the 221 flu patients died in that timespan.

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That jibes with a study published Thursday in JAMA Network Open, which found that among people 65 and over treated in U.S. Veterans Affairs hospitals, the death rate for patients with COVID-19 (6%) was nearly twice as high as for patients with the flu (3.75%).

The Israeli research underscored that COVID-19 is increasingly a disease that exacts its greatest toll on older, sicker patients. Most patients hospitalized with flu had asthma, whereas those hospitalized for COVID-19 more frequently had diabetes and high blood pressure, and needed more assistance with daily activities.

Both studies were peer reviewed by a panel of the European Congress of Clinical Microbiology & Infectious Diseases, and have been submitted to medical journals for publication.