There have been reported outbreaks of COVID-19 in some closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking, or singing.

This means that aerosol transmission, especially in indoor locations where there are crowded and inadequately ventilated spaces where infected persons spend long periods of time with others, cannot be ruled out.

WHO has called for more studies to investigate such instances and assess their significance for transmission of COVID-19.