In a large hospital in London, removing mask rules for visitors and staff did not result in a "statistically significant change" in the rate of COVID-19 infections, a study published April 6 found, adding more questions to the swirling debate of mask efficacy against the coronavirus.
For 40 weeks when omicron variants dominated, the researchers compared wards that upheld its surgical mask-wearing policies and areas of the hospital that pulled the rule in in week 26 — on June 2, 2022. They "found no evidence that a mask policy significantly impacts the rate of nosocomial SARS-CoV-2 infection."
"While these data do not preclude a small effect, the real-world benefit of this mitigation measure in isolation is likely to be modest within a healthcare setting," the researchers wrote in conclusion.
The findings suggest hospitals and other healthcare facilities could adopt "mask optional" policies and keep the risk of COVID-19 low, according to the Los Angeles Times. In the U.S., about two dozen hospitals and health systems are working to remove their mask rules, and some states are following the trend.
Many hospitals "have retained masking at significant financial and environmental cost and despite the substantial barrier to communication," said Aodhan Breathnach, MD, one of the study's authors and an infectious disease physician for the National Health Service Foundation Trust, according to the LA Times. He said he hopes the results "can help inform a rational and proportionate mask policy in health services."
Ben Patterson, MD, the lead author and a clinical lecturer at St George's University Hospitals NHS Foundation Trust in London, said the data "doesn't mean masks are worthless against omicron, but their real-world benefit in isolation appears to be, at best, modest in a healthcare setting," according to a news release.
Another study, published in late January, found similar results among more than 610,000 people in various settings in low-, middle- and high-income countries. The researchers for that study said masks "will probably make little or no difference" in the number of influenza and COVID-19 cases.