COVID-19 hitches a ride on mucus to spread deep into lungs, live imaging shows.

Investigators observed that the movement of mucus can spread the COVID-19 virus inside the respiratory tract, where it later forms aerosols that infect other people.

study on COVID-19 in auditoriums found displacement ventilation minimized infection risk, while natural ventilation had highest spread.

Masks, shorter events, and lower occupancy helped reduce risks.