Hand washing goes only so far in retarding transmission
Half of flu cases arise when people inhale tiny particles that float in the air, an international group of researchers reports June 4 in Nature Communications. The finding flies in the face of conventional wisdom, which holds that nearly all influenza spreads by large droplets that sick people release when they sneeze or cough. Those large droplets, the theory went, get on people’s hands and transmit the virus from there.
While scientists knew that small particles called aerosols represent possible routes of disease spread, they thought that cases almost never arise that way.
Public health officials say that knowing how often flu transmits via the air is important for controlling outbreaks, especially when dealing with pandemic strains for which no vaccine exists.
Benjamin Cowling, an infectious disease epidemiologist at the University of Hong Kong, and his colleagues studied how flu spread among 782 families in Bangkok and Hong Kong during re