Public health officials have been clear about it: There’s no need for healthy people to go around wearing face masks to protect themselves from the novel coronavirus. That hasn’t stopped a run on supplies, which has led to a shortage of face masks for medical personnel coping with the epidemic, who do need them. That news, in turn, has led many people to wonder why a mask that’s vital for protecting a nurse or a doctor wouldn’t help them too. Here’s what’s behind the confusion.
What do health officials say?
In its Covid-19 guidance, the World Health Organization says healthy people need to wear masks only when taking care of those who are sick or suspected of infection. The US Centers for Disease Control and Prevention “does not recommend” people who are well wear them, except in that circumstance. US Surgeon General Jerome Adams went further, tweeting, “Seriously people — STOP BUYING MASKS!” Health-care providers who can’t get masks are at risk, he said, and that in turn raises the overall risk to the community. Infected providers can spread the virus to the uninfected and once sick can’t look after patients. The Journal of the American Medical Association made the same point in an article aimed at the public. It added that there’s no evidence masks protect ordinary people going about their daily business.
Is that true?
A few small studies have suggested that widespread use of face masks by the public may have reduced transmission in outbreaks of two other respiratory diseases, influenza and severe acute respiratory syndrome, or SARS. However, the evidence is not generally considered conclusive. And with masks in short supply, the argument is that everyone is better off if they are reserved for those who actually require them and who can’t avoid exposure to people who are infected or might be.
When are regular people advised to wear masks?
If they are coughing or sneezing. A cough is a common symptom of infection with the Covid-19 virus, and the virus spreads in respiratory droplets — spatters of liquid forcefully expelled with an infected person’s cough or sneeze. These droplets are usually heavy enough to fall immediately to the ground or surrounding surfaces. Infection can occur if the droplets reach the mouth, nose or possibly the eye of someone nearby, either directly or from an unwashed hand that’s touched a contaminated object or surface. When a patient diagnosed with Covid-19 is recovering at home, they and their caregivers are advised to wear masks when they are in the same room.
What’s the guidance for health-care workers?
Medical protocols prescribe that patients suspected of infection with the Covid-19 virus be isolated and given a mask to wear. This will usually be the type worn by surgeons — the sometimes-pleated, loose-fitting, one-size-fits-all kind that’s rectangular when flat. This is to protect other people by trapping virus-containing respiratory droplets. Health-care providers who deal with such patients or with confirmed cases are directed to wear a more sophisticated mask called a respirator. These are designed to protect the user.
How are respirators different?
They come in different sizes so they can be fit to the wearer’s face to provide a tight seal. That forces the user to pull air through the device’s filter rather than through gaps on the sides. They are designed to keep out not only respiratory droplets but also smaller aerosolised particles that can carry infectious agents and float for a time through the air. Airborne transmission has not been reported for Covid-19, but there is a risk that certain medical procedures, such as tracheotomy and airway suction, can generate aerosols. Respirators are uncomfortable to wear for a long period of time. They generate heat and exert pressure on the face, and some people find they make it difficult to breathe, which can make them unsuitable for those with cardiac and respiratory conditions.
Are there downsides to wearing a mask?
Adams said that people who aren’t trained in how to use them tend to touch their faces a lot, which could increase their chances of becoming infected with the coronavirus. The WHO emphasises that if you’re going to use a mask, it’s vital to do so correctly: put them on with clean hands, remove them from behind without touching the front and washing hands afterward, never re-use single-use masks, dispose of them properly.
The reference shelf
Guidance on masks from the World Health Organization, the US Centers for Disease Control and Prevention and the Journal of the American Medical Association.
The US Food and Drug Administration’s primer on surgical masks and medical respirators.
An analysis by the digital magazine Sapiens on why so many people are wearing masks.