Photo: Kevin Dietsch/UPI
While Americans continue to debate whether face masks can stop the spread of coronavirus, a new report offers compelling evidence that the coverings do indeed work.
In May, two hairstylists at a Missouri salon who had COVID-19 but wore face masks cut the hair of 139 masked customers for roughly a week, and did not infect a single client. They also did not infect any of the clients' contacts or any of the other stylists in the salon, researchers report.
The first stylist worked with clients for eight days while symptomatic, while the second stylist did the same for five days, the researchers wrote.
"The message is clear: Face masks work," said Dr. Robert Glatter, an emergency room physician at Lenox Hill Hospital in New York City. "They prevent transmission of COVID-19 from those who are symptomatic and asymptomatic." He was not involved with the study.
"We need to enforce the wearing of face masks in all indoor activities due to poor ventilation that increases risk of transmission," Glatter added.
The authors of the new report concurred.
"These results support the use of face coverings in places open to the public, especially when social distancing is not possible, to reduce the spread of SARS-CoV-2," they concluded.
"With the potential for pre-symptomatic and asymptomatic transmission, widespread adoption of policies requiring face coverings in public settings should be considered to reduce the impact and magnitude of additional waves of COVID-19," researchers said.
Some of the close contacts of the stylists did not fare as well, the report authors noted. All four contacts of the first stylist, who lived in the same home, later tested positive for COVID-19, while none of the close contacts of the second stylist became symptomatic.
The report was published July 14 in the CDC publication Morbidity and Mortality Weekly Report.
The research team, led by Dr. Robin Trotman, an infectious disease specialist based in St. Louis, noted several limitations to the findings.
While the local health department monitored all exposed clients for symptoms of COVID-19, only 67 were actually tested and any COVID-19 tests done too early might have come back false negative, the researchers said.
No information was collected on underlying medical conditions or use of other personal protections such as gloves and hand hygiene, any clients who interacted with the stylists before they developed symptoms were not recruited for contact tracing and most stylists cut hair while clients are facing away from them, which might have limited transmission, the researchers said.
Still, "consistent and correct use of face coverings, when appropriate, is an important tool for minimizing the spread of SARS-CoV-2 from pre-symptomatic, asymptomatic, and symptomatic persons," the researchers concluded.
Dr. Eric Cioe Pena, director of global health at Northwell Health in New Hyde Park, N.Y., reviewed the findings and put it more bluntly.
The report is "a very powerful message about how much of a game-changer face coverings and masks have been in fighting coronavirus," he said.
"It is probably the single most effective public health measure that we have taken to date. This should not be controversial, it is good science and has the potential to allow us to return as closely as possible to a normal economic situation as quickly as possible.
"The level of infectiousness of a person wearing a mask is markedly reduced and they may be protecting you from getting infected before they even know they are sick," Pena added. "Ignore the utility and use of face coverings at your own peril."