Everyone should routinely wear cloth face masks when they are in contact with the public to reduce transmission of the new coronavirus that causes COVID-19, according to new guidance from the Centers for Disease Control and Prevention (CDC).

“It is critical to emphasize that maintaining six-feet social distancing remains important to slowing the spread of the virus. CDC is additionally advising the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others,” the CDC’s updated website states. “Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.”

This is a departure from previous public health recommendations that people should not routinely wear masks unless they have symptoms or are caring for someone who is ill. Now, people are advised to wear cloth masks when shopping for groceries, going to work at essential jobs or whenever they might encounter people outside their household.

The earlier recommendation was based on the fact that face masks do not offer complete protection, especially if they are not worn correctly. What’s more, badly needed N95 respirators and surgical masks—which are both in short supply—should be saved for health care providers and other frontline workers.

“Those are critical supplies that must continue to be reserved for health care workers and other medical first responders,” the CDC emphasizes.

The updated guidelines were announced during the daily White House coronavirus briefing on Friday, after some hard-hit cities including Los Angeles and New York had already advised residents to wear face masks in public. President Donald Trump stressed that the new mask recommendation is voluntary and said he is choosing not to wear one.

What We Know 

As the coronavirus epidemic has worsened in the United States, there’s been growing agreement that cloth masks, while not perfect, can help reduce the spread of the virus. Even if they offer only a modest benefit for any given individual on any specific occasion, these small effects can add up to substantial risk reduction at the population level.

 

N95 respirator masks block tiny particles including bacteria and viruses. They must be fitted properly to ensure a tight seal, and they can be uncomfortable for long-term use. Medical procedure or surgical masks don’t filter out virus particles, but they do block respiratory droplets that carry bacteria and viruses. These droplets are expelled when people cough or sneeze, and the virus is released into the air even when they sing, talk or breathe.

 

The cloth masks the CDC recommends are more like surgical masks, but usually without a filter layer. They are easy to make yourself, and many crafters sell them in a wide variety of colors and patterns (see Etsy, for example). One recent comparison found that masks made from a double layer of heavy-duty cotton appear to work well. Even a bandana or cut-up T-shirt can reduce the spread of virus-containing droplets. Make sure your mask fits snugly and completely covers your mouth and nose.

The CDC’s updated recommendation is based on increasing evidence that face masks can reduce respiratory virus transmission.

Some past studies have shown that societies where people routinely wear masks tend to have lower flu rates than those that don’t. And in the current pandemic, some countries where mask use is a normal habit, including South Korea and Taiwan, have gotten an early handle on their local outbreaks.

 

A recent study in the journal Nature found that surgical masks significantly reduce the release of respiratory viruses by the wearer. As the authors of a 2008 study concluded, “Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence.”

More recent research shows that people can transmit the new coronavirus even when they have no symptoms. For this reason, it’s not enough to wear a mask only if you feel ill or are in contact with someone who is ill.

Some studies suggest that up to a quarter of people who contract the coronavirus may be asymptomatic. The Los Angeles Times recently reported that more than 40 people in Seattle became ill with COVID-19 and two died after attending a two-hour choir practice, even though none of the members had symptoms and they avoided any physical contact.

In addition to blocking the spread of the virus through the air, wearing a mask can remind you not to touch your face, which can transmit virus left on surfaces such as door handles.

 

Plus, widespread mask use reduces stigma. “One advantage of universal use of face masks is that it prevents discrimination [against] individuals who wear masks when unwell because everybody is wearing a mask,” wrote the authors of a recent commentary in The Lancet.

 

While masks have been a controversial issue, something approaching a consensus is emerging in favor of voluntary mask use by the general public in communities where the coronavirus is spreading. Recent reports from both Yale and the conservative American Enterprise Institute support universal use of cloth masks.

Health officials stress that wearing a face mask is not a substitute for social distancing. If the coronavirus is spreading in your community, you should still stay at home as much as possible, wash your hands often and try to stay at least six feet away from other people.

But unless you never leave home—and no one in your household does either—you could be carrying the coronavirus and not know it. By wearing a simple cloth mask, you can help protect both yourself and others.

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