Medical face masks are often used during flu season or a virus outbreak — and photos of people wearing them have come to be a defining symbol during a health scare. Most people wear surgical masks, while health workers wear stronger masks that are individually fitted. Experts say masks can be effective in preventing the spread of most respiratory viruses that are transmitted through droplets in the air or on surfaces. However, like most preventative measures, it is not a catch- all solution. In the case of Coronavirus, which began spreading in China in January 2020, authorities have encouraged everyone to wear face masks — even as health experts work to determine how exactly the virus spreads. Demand for face masks skyrocketed in China, forcing Chinese face mask manufacturers to reopen factories during the Lunar New Year holiday break. In the U.S., experts say wearing a mask to protect from Coronavirus is not necessary.