Nursing homes are the most common setting for superspreading events in the database. How can the virus spread so easily in them? A confidential report of the Dutch scientific advisory board RIVM may provide an answer. It states that the HVAC system in a nursing home in the Netherlands likely caused an outbreak that infected up to 21 residents and 18 staff members. Below is a (slightly manually improved) Google Translate of an article in Dutch newspaper De Volkskrant. The main findings that are suggestive of aerosol transmission via the HVAC system: - All staff members in the nursing home wore surgical masks (except during breaks) - Only one patient was initially infected but the virus then spread rapidly throughout the facility - The virus was found in high values ​​on the mesh covers of the air-conditioning unit and in filters of four ventilation cabinets.