Non-woven Masks and SARS-CoV-2 Infection in a Cluster Setting in Japan

Evidence regarding the types of masks that are effective in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is limited. We identified the mask types that were effective against SARS-CoV-2 infection in a cluster setting in Japan. Data from a cluster of employees with coronavirus disease 2019 at a manufacturing company in mid-August 2021 were retrospectively reviewed. A total of 87 employees who reported the type of mask worn were included. The types of masks were dichotomized into non-woven masks or other types of masks, such as cloth or urethane masks. The association between mask type and SARS-CoV-2 infection was determined using logistic regression analysis after adjusting for potential confounders. Participants who wore non-woven masks were less likely to be infected with SARS-CoV-2 (9.7%) than those who wore other types of masks (26.7%). After adjusting for potential confounders, wearing a non-woven mask was significantly associated with a reduced risk of infection compared to wearing other types of masks (odds ratio, 0.10; 95% confidence interval, 0.01-0.80). Non-woven masks were more effective in preventing SARS-CoV-2 infection in a cluster setting than other types of masks, such as cloth or urethane masks.