TORONTO — Face masks made with multiple layers of cotton cloth may help prevent further transmission of COVID-19, according to an international team of researchers who examined a century’s worth of mask studies.
Homemade cloth masks aren’t perfect, they found, but they may help provide a “modest reduction in transmission” if widely used.
“Given the severity of this pandemic and the difficulty of control, we suggest that the possible benefit of a modest reduction in transmission likely outweighs the possibility of harm,” the team wrote in a paper published in the Annals of Internal Medicine on May 22.
The novel coronavirus SARS-CoV-2 is transmitted through aerosol and droplet particles that people generate while speaking, eating, coughing and sneezing. A cloth mask can stop those particles in their tracks before they can transmit the virus.
“Every virus-laden particle retained in a mask is not available to hang in the air as an aerosol or fall to a surface to be later picked up by touch,” the researchers said.
There is insufficient evidence as to whether a mask works as well to protect a wearer as it protects others from the wearer’s droplets, said lead author Catherine Clase, associate professor of medicine at McMaster University and a nephrologist of St. Joseph’s Healthcare in Hamilton, Ont., in a press release.
“Ideally, we would want a mask to work in both directions, protecting the wearer from the environment and reducing the contamination of the environment — air and surfaces — by the wearer,” she said.
While the research is incomplete, there is enough “convincing” evidence that should “suffice to inform policy decisions on their use in this pandemic pending further research,” the researchers wrote.