We all want to protect ourselves from corona virus, but we need to make sure the things were doing are effective. There are several measures we can all take to reduce the spread of Covid-19, including physical distancing, thorough hand washing, keeping surfaces clean, protecting the most vulnerable by staying home, and isolating ourselves if we have symptoms. We know from scientific evidence, as well as what we have learned from other countries further ahead in their epidemics, that these things work.
When someone with Covid-19 wears a face mask, they can prevent other people from being infected. It’s also vital for healthcare workers to wear face masks (and to have masks available to wear), both during surgery and routine procedures, to prevent patients becoming infected. Health workers are highly trained experts who know how to correctly use face masks. The masks they use are medical grade equipment and are far more effective than their cloth alternatives.
What do masks do?
Face masks are used primarily by people in the community to prevent sick people from spreading infection. COVID-19 is mostly spread via respiratory droplets — the little secretions we generate when we sneeze or cough a and face masks can help to catch some of these fluid splashes.
The US Centers for Disease Control and Prevention recently updated its guidelines to recommend all Americans wear cloth or fabric face coverings when they’re in a public place. This is to reduce the spread of infection by asymptomatic people (meaning they’re sick with COVID-19 but show no symptoms), according to Abrar Chughtai, an infectious disease epidemiologist at the University of New South Wales. “Those asymptomatic cases can transmit infection, so due to that reason, the CDC is recommending everyone use masks, because we don’t know who is sick and who is healthy,” Dr Chughtai said.
There is a lack of good, robust evidence on the effectiveness of standard face mask worn by the public. One of the best forms of evidence in medical research is a randomized controlled trial. Typically, these are blinded, where information that may influence participants is withheld until after the experiment is completed. We would have difficulty doing this kind of trial of face masks, because it’s impossible for participants to be unaware of whether or not there wearing a mask.