Masks provide extreme risk reduction for others if the wearer has the virus. Combine that with the 2-week incubation period and masks are quite effective. Mas

Masks provide extreme risk reduction for others if the wearer has the virus. Combine that with the 2-week incubation period and masks are quite effective. Mask wearing was a law in SF during the 1918 epidemic and saved many lives. Once again, history is forgotten.