A brief published on July 9 by the World Health Organization states that WHO is evaluating whether SARS-CoV-2 may spread through aerosols in indoor settings. According to the brief, some reports of outbreaks related to crowded indoor spaces have suggested the possibility of aerosol transmission combined with droplet transmission. “In these events, short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons cannot be ruled out,” WHO’s brief explains. “However, the detailed investigations of these clusters suggest that droplet and fomite transmission could also explain human-to-human transmission within these clusters.” The organization states that further studies are needed to determine what role aerosols might play in transmission in these types of settings.  WHO’s scientific brief incorporates additional new evidence available on the transmission of SARS-CoV-2. The brief was published a few days after an open letter from more than 200 scientists in Clinical Infectious Diseases urged public health organizations like WHO to address the potential for airborne spread of COVID-19.