Growing evidence that people without symptoms can spread COVID-19 last week prompted the federal Centers for Disease Control to recommend everyone wear masks when mingling with others in public.
Medical experts initially assumed that people mostly spread the virus when they coughed or sneezed once they developed symptoms.
Therefore, most held off recommending people without symptoms wear masks, which also prevented a run on masks needed by nurses, hospital and emergency workers now facing a global shortage.
However, a growing number of studies suggests anywhere from 25% to 50% of those infected can spread the virus for weeks before any symptoms develop. The average incubation time is 5-12 days for a person to develop symptoms.
Moreover, masks may also help slow the spread of the virus by preventing people from touching their mouth and nose if they’ve gotten the virus on their hands from a contaminated surface. The virus can survive on surfaces for hours — especially smooth, hard surfaces. However, experts suspect most infections come from direct contact.
The CDC therefore shifted its recommendation, although trying to craft the recommendation in a way that won’t increase the demand for the surgical masks in desperately short supply for doctors and nurses.
“In light of this new evidence, CDC recommends wearing cloth face coverings in public settings where other social distance measure are difficult to maintain (grocery stores and pharmacies) especially in areas of significant community-based transmission,” said the CDC on its website (https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover.html). The website also has a video on how to make your own mask.
The recommendation underscored the need to maintain the six-foot “social distancing” interval.
“The cloth face coverings recommended are not surgical masks or N-95 respirators. Those are critical supplies that must continue to be reserved for health care workers and other medical first responders,” said the freshly issued guidelines.
Laboratory tests have confirmed that surgical masks significantly reduce the viral particles an infected person puts into the air, according to a summary of research by researchers from the University of Maryland posted on the website ScienceDaily and published in the journal Nature Medicine.
That study focused on whether the masks reduce the viruses load released into the air by someone who was infected. It didn’t consider whether wearing a mask will protect an uninfected person.
“In normal times, we’d say that if it wasn’t shown statistically significant or effective in real-world studies,” said Dr. Don Milton about whether the mask will prevent people from becoming infected. “But in the middle of a pandemic, we’re desperate. The thinking is that even if it cuts down transmission a little bit, it’s worth trying.”
So far, most of the infections with COVID-19 have been linked to clusters of people who shared close contact over an extended period — like family members. Studies have shown the virus most often travels in small droplets, which drop to the ground pretty quickly. Sometimes, the virus can survive in aerosol form for several hours, but it’s unclear how frequently the virus infects someone in that form.
Masks can significantly reduce both droplet and aerosol forms of the virus produced by an infected person. That’s not true of all types of virus — but appears to apply to COVID-19.
Other measures are even more effective, like improving ventilation and installing UV-C lights near the ceiling in combination with fans that pull air upward. Contact with the lights will destroy the virus. The risk of spreading COVID-19 appears greater in enclosed and poorly ventilated spaces than outdoors.
Meanwhile, the inspector general of the U.S. Department of Health and Human Services this week issued a report that hospitals face a critical shortage of supplies, including protective gear, tests and ventilators.
The U.S. has nearly depleted supplies of such items in the national emergency strategic stockpile.
States have been literally outbidding one another in an attempt to secure normally plentiful items like masks, gowns and gloves, mostly manufactured in China and other overseas markets where existing supply chains have been disrupted.
The CDC has urged the public to use cloth masks, rather than the disposable surgical masks used by doctors and nurses.