Surgical mask use by healthcare personnel to prevent COVID-19 spread in a long-term care facility.

Long-term care facilities are a recognized high-risk setting for severe outcomes during the coronavirus disease 2019 (COVID-19) outbreak. This study describes a COVID-19 outbreak in a long-term care facility in Japan. The index case was a nurse who wore a surgical mask and used standard precautions. Of the 17 confirmed cases of COVID-19, 14 (14/93, 15.1%) were residents and three (3/69, 4.3%) were healthcare personnel (HCP); no visitors tested positive 0 (0/22, 0.0%). Mask utilization by HCP was not much effective in preventing COVID-19 transmission, even when interaction was not considered as being in close contact.