Prospective Cohort; Other
Study population and setting
Authors investigated the potential effectiveness of face coverings through a case study of two hair stylists (Stylists A and B) in Springfield, Missouri who served 139 clients from the moment they exhibited symptoms of COVID-19 (May 12, 2020 and May 15, 2020 respectively) until they tested positive and took leave from work (May 20, 2020 and May 22, 2020 respectively). Springfield issued a city-wide ordinance on May 6, 2020 restricting indoor capacity in waiting areas to 25%, and recommending the use of face coverings as well as social distancing measures. The salon also recommended the use of such coverings for clients and stylists alike. Although Stylists A and B interacted with each other without any face coverings in between clients, they indicated having worn either a “double-layered cotton face covering” or a surgical mask when interacting with their clients.
Summary of Main Findings
Additional stylists working closely with Stylists A and B in the same hair salon did not report any manifestations of COVID-19 symptoms in the two weeks following their exposure. However, all four household contacts of stylist A tested positive. Of the 67 clients (48.2%) who agreed to be tested, all tested negative. Interactions between stylists and clients ranged from 15 to 45 minutes in duration. Of the 104 (74.8%) clients who agreed to be interviewed, 102 (98.1%) indicated that they wore a face covering for the entire duration of their appointment. Clients wore diverse types of face coverings, though most wore cloth face coverings (47.1%) or surgical masks (46.1%). The majority of clients interviewed (101/104, 97.1%) reported that their stylist had used a face covering for the duration for their appointment.
A large number of household and work-related contacts were tested for COVID-19 following prolonged indoor exposure to two known infectious cases who wore face coverings while at work and interacting with clients. While no work-related transmissions were documented when face coverings were used, transmissions occurred both at work and in the home in the absence of their use.
While all clients were monitored for symptoms, less than half (48.2%) were tested; differences between the testing and non-testing subsets are not disclosed. Biases may have been introduced if those clients who tested exhibited higher levels of health-seeking behaviours (and thus less likely to acquire COVID-19) than those who did not. Additionally, clients may have also declined to participate in testing due to possible concerns or stigma associated with testing positive for COVID-19. The absence of reported symptoms does not indicate absence of a COVID-19 infection; clients who reported an absence of symptoms or who declined to be tested may have been asymptomatic, limiting our understanding of face coverings with regards to asymptomatic transmission. Authors acknowledge limitations introduced by false-negative testing results. Additional information about protective measures that clients may have taken to reduce risk in the salon (wearing gloves, hand-washing) were not collected. Information about the use of air ventilation systems or open windows to reduce risk in the salon is also not disclosed. Due to the nature of the work, stylists mostly worked with clients facing away from them, which might have limited direct exposure to infected droplets or other forms of transmission.
This study contributes to a limited existing empirical literature on face coverings to control COVID-19 spread, and makes a compelling case for their effectiveness.
This review was posted on: 28 July 2020