But studies of influenza pandemics have shown that when high-grade N95 masks are not available, surgical masks do protect people a bit more than not wearing masks at all. And when masks are combined with hand hygiene, they help reduce the transmission of infections.

When researchers conducted systematic review of a variety of interventions used during the SARS outbreak in 2003, they found that washing hands more than 10 times daily was 55 percent effective in stopping virus transmission, while wearing a mask was actually more effective — at about 68 percent. Wearing gloves offered about the same amount of protection as frequent hand-washing, and combining all measures — hand-washing, masks, gloves and a protective gown — increased the intervention effectiveness to 91 percent.