How wearing masks cut coronavirus transmission to 139 clients in a salon

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Vigilant mask wearing by two hair stylists working at a salon in Springfield, Missouri in the U.S. and all the 139 clients they served in mid-May helped prevent the spread of novel coronavirus to the clients. But the study did not trace and test those clients who had interacted with the two stylists days before the stylists started exhibiting symptoms.

The case for wearing masks to cut the risk of coronavirus transmission just got stronger. Vigilant mask wearing by two hair stylists working at a salon in Springfield, Missouri in the U.S. in mid-May from the day they developed symptoms helped prevent 139 clients they served from getting infected.

Neither the clients nor their contacts, who were traced and followed up for two weeks, developed any symptoms of COVID-19. One month after contact tracing, 104 of 139 clients were interviewed over telephone. Among the 104 who were interviewed, 102 (98.1%) reported wearing a mask throughout the time of appointment while two reported wearing a mask part of the time. But both stylists were wearing a mask during the entire duration of each appointment. While one stylist was wearing a double-layered cotton mask, the other was wearing a double-layered cotton mask or a surgical mask.

The clients were offered testing five days after exposure, or as soon as possible for those exposed more than five days before contact tracing began. In all, 67 (48.2%) clients volunteered to be tested and none was found infected for the virus by RT-PCR. The results of the study were published in the Morbidity and Mortality Weekly Report.

Close contact

The stylists came in close contact with their clients seeking haircuts, facial hair trimmings, and perms for a period ranging from 15 to 45 minutes but yet did not transmit the virus to them. While the duration of close contact may be sufficient for virus spread, the mode of interaction duration the contact did not involve talking, sneezing or coughing. Also, most of the clients who got a haircut were facing away from the stylists, which might have also reduced the risk of transmission.

There is a body of evidence to show that virus transmission is “highest during the two-three days before symptom onset”. Though rate of transmission of the virus before symptoms show up is not clear, asymptomatic people are “likely to contribute to virus spread”. Yet, the study did not trace and test those clients who had interacted with the two stylists days before the stylists started exhibiting symptoms.

Importance underscored

The role of masks in preventing transmission of the virus is underscored by the fact that the first stylist possibly infected the other stylist during those periods between clients when neither wore a mask. Also, one of the stylists infected four others who were living with her.

The first stylist who was infected worked for eight days even when symptoms showed up. She stopped working only when results of RT-PCR test returned positive. The second stylist developed respiratory symptoms three days after the first stylist exhibited symptoms. The second stylist worked for five days even while exhibiting symptoms before self-isolating and getting tested.

“These results support the use of face coverings in places open to the public, especially when social distancing is not possible, to reduce spread of SARS-CoV-2,” the authors write.

Mask not a substitute

According to World Health Organization June 5 guidelines for both healthy and infected people, “the use of masks is part of a comprehensive package of the prevention and control measures that can limit the spread of certain respiratory viral diseases, including COVID-19. However, the use of a mask alone is insufficient to provide an adequate level of protection or source control, and other personal and community level measures should also be adopted to suppress transmission of respiratory viruses.”

“WHO supports the use of masks as one of the tools that can be put in place. However, it is not a substitute for other public health measures – hand hygiene, physical distancing, testing, contact tracing, etc. – all of this must be done together,” Dr Maria Van Kerkhove, Infectious Disease Epidemiologist at WHO tweeted.

The European Centre for Disease Prevention and Control (ECDC) echoes the same message: “The use of face masks in the community should be considered only as a complementary measure and not as a replacement for established preventive measures, for example physical distancing, respiratory etiquette, meticulous hand hygiene and avoiding touching the face, nose, eyes and mouth.”

Published in The Hindu on July 25, 2020

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