Surgical masks are a basic defense against some viruses, and they may be helpful in communities where health officials suspect viruses are circulating widely.
But in the US, there's no need to wear surgical masks -- or the N95 respirators physicians wear when treating viruses -- says infectious disease expert Dr. Charles Chiu.
There's no evidence of sustained novel coronavirus transmission in the US like there is in China, and the Centers for Disease Control and Prevention has not recommended Americans wear masks in public.
"Right now, there's no evidence that [wearing face masks] is going to help prevent that infection," Chiu, a professor of laboratory medicine at the University of California, San Francisco, told CNN. "I would not recommend that someone in the US who does not have direct exposure, did not recently travel to China...or in general that you go buy a face mask."
Physicians wear masks, but the US public shouldn't
Americans are scooping up two kinds of masks
- Surgical masks
- N95 respirators
The CDC doesn't recommend public citizens wear either of them.
Surgical masks: While they do protect from large respiratory droplets (a spray from a sneeze or mucus from a cough), they don't prevent against airborne droplets. Surgical masks aren't considered respiratory protection by the CDC because they don't filter smaller particles, and therefore isn't effective in totally preventing coronavirus transmission.
"Wearing a surgical mask helps you prevent sharing your germs if you're sick," Saskia Popescu, a hospital epidemiologist and infection prevention expert, told CNN. "Surgical masks do not seal around the face, so while they offer some protection, it's the N95 mask that offers the most protection."
N95 respirators: Should you wear an N95 respirator depends on whether you're a physician involved in a particular task.
The CDC does recommend that healthcare providers wear N95 respirators, face masks that filter at least 95% of airborne particles, if they treat a patient infected with the novel coronavirus.
In the case of SARS, another type of coronavirus, a large amount of infections originated in hospitals among healthcare workers treating infected people, Chiu said. So now, doctors follow the same strict precautions and wear gowns, gloves, N95 respirators and goggles to reduce their likelihood of infection.
So unless you're treating a patient with the coronavirus, the N95 respirator isn't necessary, he said.
Another reason not to wear an N95 mask: Physicians are also regularly fitted for the N95 respirators, and there's a proper way to wear them to ensure there's no open space and the mask fits snugly against the face. People with no medical training might wear it incorrectly, Popescu said.
Plus, Chiu said, N95 respirators are "quite uncomfortable" to wear for long periods of time -- and taking it off negates the effects of wearing it.
Masks could give wearers a false sense of security
In China's Heibo Province where the coronavirus is thought to be actively spreading, surgical masks aren't a fail-safe, but they're "better than nothing," Popescu said.
But in the US, Chiu said, wearing a mask could give wearers a "false sense of security," he said: If concerned people wear a surgical mask, usually made out of thin fabric or paper, they may not continually wash their hands or fear contact with infected people.
"That's really not the nature of transmission," he said. "That's thought to be contact transmission -- touching infected surfaces, touching the eyes and nose."
Chiu and the CDC recommend what he calls "common-sense measures": Avoid contact with ill people, stay home from work when sick, thoroughly wash hands with soap.
The CDC's recommendations for response in the US could change as the situation does. But at this point, Americans don't need to wear masks in public.
"We should certainly continue to monitor the situation closely, but right now is not the time to panic," he said.