3. the Journal of Hospital Infection in 2003 found that medical masks were effective in reducing the spread of the SARS coronavirus during the 2003 SARS outbreak in Hong Kong.
4. A randomized controlled trial published in the Annals of Internal Medicine in 2009 found that the use of medical masks by household contacts of people with influenza-like illness was associated with a significant reduction in the incidence of laboratory-confirmed influenza.
5. Another randomized controlled trial published in the American Journal of Respiratory and Critical Care Medicine in 2010 found that the use of medical masks by healthcare workers was associated with a significant reduction in the incidence of respiratory viral infections.