Dr. Matt McCarthy - Assistant Professor of Medicine at Weill Cornell,staff physician at New York-Presbyterian Hospital, and author of Superbugs: The Race to Stop an Epidemic- claims that the CDC is about to do a 180 degree change, and to recommend that everyone wear masks.
If true, such a change would be very helpful. Specifically, numerous studies show that "facemasks play a pivotal role in the prevention and control of infectious respiratory disease transmission".
Indeed, a study last year by scientists at the Departments of Chemical & Biomolecular Engineering, University of Maryland, and the FDA's Division of Applied Mechanics, showed that - if 80% of a population wears masks - it will stop a flu epidemic (it "essentially eliminated the influenza outbreak"). They found that if half of a population wore masks, it "resulted in a significant ... reduction in risk" (the typical flu virus is between 80 and 120 nanometers in diameter. The Wuhan Coronavirus is 120 nanometers).
Many other studies and metastudies show that masks are effective in combatting respiratory virus pandemics:
The New York Times notes:
As the coronavirus pandemic rages on, experts have started to question official guidance about whether ordinary, healthy people should protect themselves with a regular surgical mask, or even a scarf.
When researchers conducted systematic review of a variety of interventions used during the SARS outbreak in 2003, they found that washing hands more than 10 times daily was 55 percent effective in stopping virus transmission, while wearing a mask was actually more effective — at about 68 percent. Wearing gloves offered about the same amount of protection as frequent hand-washing, and combining all measures — hand-washing, masks, gloves and a protective gown — increased the intervention effectiveness to 91 percent.
With the current coronavirus, researchers are also finding that there are more asymptomatic cases than were known early on in the pandemic. Classified data from the Chinese government that was reported in the South China Morning Post indicated that up to a third of all people who tested positive for the coronavirus could have been silent carriers. Widespread testing on the Diamond Princess showed that half of the positive cases on board the cruise ship had no symptoms. And officials in Iceland, who have tested a high proportion of citizens in the country, have found similarly high percentages of asymptomatic infection.
Since identifying and isolating people with infections plays a major role in breaking the chain of transmissions, people who do not have any symptoms or do not develop symptoms until later may continue to inadvertently spread the disease.
And places like Hong Kong and Taiwan that jumped to action early with social distancing and universal mask wearing have gotten their cases under much greater control.“If everyone in the community wears a mask, it could decrease transmission,” Dr. Fishman said.
Science Magazine writes:
Despite messages from some health officials to the contrary, it’s likely that a mask can help protect a healthy wearer from infection, says Benjamin Cowling, an epidemiologist at the University of Hong Kong. Both surgical masks and the more protective N95 respirators have been shown to prevent various respiratory infections in health care workers; there’s been some debate about which of the two is appropriate for different kinds of respiratory infection patient care. “It doesn’t make sense to imagine that … surgical masks are really important for health care workers but then not useful at all for the general public,” Cowling says.
But the greatest benefit of masking the masses, Cowling and others argue, likely comes not from shielding the mouths of the healthy but from covering the mouths of people already infected. People who feel ill aren’t supposed to go out at all, but initial evidence suggests people without symptoms may also transmit the coronavirus without knowing they’re infected. Data from contact-tracing efforts—in which researchers monitor the health of people who recently interacted with someone confirmed to have an infection—suggest nearly halfof SARS-CoV-2 transmissions occur before the infected person shows symptoms. And some seem to contract and clear the virus without ever feeling sick. “If I knew who was asymptomatic and presymptomatic [for COVID-19], I’d … triage the face masks to those individuals,” Monto says. Unfortunately, he adds, “We don’t know who these are.”
The problem, of course, is there is a massive shortage of protective equipment for healthcare workers in America and worldwide. As such, N95 respirators need to be saved for healthcare workers first ... and people should not be buying them for themselves.
The good news is that even homemade masks help ...
A scientist at the National Institute for Public Health and the Environment in the Netherlands reports:
All types of masks reduced aerosol exposure .... Personal respirators were more efficient than surgical masks, which were more efficient than home-made masks.
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, personal respirators providing most protection.
British scientists found that homemade masks made by people who didn't know what they were doing were about one-third as effective as surgical masks ... partly because they did not fit very well.
But health experts have released plans for homemade masks which work much better ...
For example, a mask made from common household and office materials, which was designed by a scientist from the University of Hong Kong-Shenzhen Hospital, was shown in lab tests be 80-90% as effective as surgical masks.
Better yet, healthcare professionals from Unity Point Health in Iowa (which runs St. Lukes Hospital) have designed a diy mask which could be as effective as an N95 respirator (the gold standard for frontline healthcare providers).
Specifically, an N95 has .3 micron pores, and is 95% effective at filtering out .3 micron viruses.
Hepa filters (like those made for allergy-reducing air filters and vaccuum cleaners) also have .3 micron pores. So sewing a washable mask with a pocket to slide in a piece of Hepa filter may work really well ... especially if steps are taken to make sure that the mask is "fit-tested":