Answer:

Can face masks help slow the spread of the coronavirus (SARS-CoV-2) that causes COVID-19? Yes, face masks combined with other preventive measures, such as frequent hand-washing and social distancing, help slow the spread of the virus.

So why weren't face masks recommended at the start of the pandemic? At that time, experts didn't know the extent to which people with COVID-19 could spread the virus before symptoms appeared. Nor was it known that some people have COVID-19 but don't have any symptoms. Both groups can unknowingly spread the virus to others.

These discoveries led public health groups to do an about-face on face masks. The World Health Organization and the U.S. Centers for Disease Control and Prevention (CDC) now include face masks in their recommendations for slowing the spread of the virus. The CDC recommends cloth face masks for the public and not the surgical and N95 masks needed by health care providers.

How do the different types of masks work?

Surgical masks

Also called a medical mask, a surgical mask is a loose-fitting disposable mask that protects the wearer's nose and mouth from contact with droplets, splashes and sprays that may contain germs. A surgical mask also filters out large particles in the air. Surgical masks may protect others by reducing exposure to the saliva and respiratory secretions of the mask wearer.

At this time, the U.S. Food and Drug Administration has not approved any type of surgical mask specifically for protection against the coronavirus, but these masks may provide some protection when N95 masks are not available.

N95 masks

Actually a type of respirator, an N95 mask offers more protection than a surgical mask does because it can filter out both large and small particles when the wearer inhales. As the name indicates, the mask is designed to block 95% of very small particles.

Health care providers must be trained and pass a fit test to confirm a proper seal before using an N95 respirator in the workplace. Like surgical masks, N95 masks are intended to be disposable. However, researchers are testing ways to disinfect N95 masks so they can be reused.

Some N95 masks, and even some cloth masks, have one-way valves that make them easier to breathe through. But because the valve releases unfiltered air when the wearer breathes out, this type of mask doesn't prevent the wearer from spreading the virus. For this reason, some places have banned them.

Cloth masks

A cloth mask is intended to trap droplets that are released when the wearer talks, coughs or sneezes. Asking everyone to wear cloth masks can help reduce the spread of the virus by people who have COVID-19 but don't realize it.

Cloth face coverings are most likely to reduce the spread of the COVID-19 virus when they are widely used by people in public settings. And countries that required face masks, testing, isolation and social distancing early in the pandemic have successfully slowed the spread of the virus.

While surgical and N95 masks may be in short supply and should be reserved for health care providers, cloth face coverings and masks are easy to find or make, and can be washed and reused.

Masks can be made from common materials, such as sheets made of tightly woven cotton. Instructions are easy to find online. Cloth masks should include multiple layers of fabric. The CDC website even includes directions for no-sew masks made from bandannas and T-shirts.

Explanation:

A paper discussed below has been retracted by the journal the Annals of Internal Medicine. The authors wrote that their statistical methods could not determine whether the findings were reliable, making the results of the small study "uninterpretable." The study had found that surgical and cotton masks do not effectively contain viral droplets containing SARS-CoV-2. Subsequent research has suggested that face masks are an effective method for containing the spread of the virus, used along with staying six feet apart from other people.

For the first time, the Center for Disease Control and Prevention (CDC) has recommended that even seemingly healthy people wear masks over their mouths and noses when venturing out of their homes into places where it is difficult to maintain distance from other people. But there is still major debate over how much masks — particularly the homemade fabric masks that the CDC recommends for the public — can slow the spread of SARS-CoV-2, the virus that causes COVID-19.

Researchers, writing in two new papers, attempt to tackle the efficacy of masks, one more rigorously than the other, and come to differing conclusions. One study examined the effect of masks on seasonal coronaviruses (which cause many cases of the common cold) and found that surgical masks are helpful at reducing how much virus a sick person spreads. The other looked particularly at SARS-CoV-2 and found no effect of either surgical or fabric masks on reducing virus spread, but only had four participants and used a crude measure of viral spread.

The bottom line, experts say, is that masks might help keep people with COVID-19 from unknowingly passing along the virus. But the evidence for the efficacy of surgical or homemade masks is limited, and masks aren't the most important protection against the coronavirus