A new report from a hair salon in Springfield, Missouri shows that wearing a face mask is not only altruistic, but also helps prevent the person wearing it from contracting COVID-19.
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And some infectious disease experts increasingly believe that wearing a mask could mean that even if a person is infected, they are more likely to have a milder or even asymptomatic form of the disease.
The Missouri hair salon case was published in this week’s Centers for Disease Control and Prevention Morbidity and Mortality Report. It is an example of the power of face masks to stop the spread of SARS-CoV-2, the virus that causes COVID-19.
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On May 12, a stylist from a Springfield Great Clips salon developed respiratory symptoms, but continued to work for eight days until a COVID-19 test tested positive.
Another stylist started to get sick three days later and worked another seven days before testing positive and staying home. Both colleagues wore masks only when clients were present.
Six close contacts of the first stylist ended up coming with COVID-19. But in the salon, where 98% of the clients wore masks, things developed differently. Of the 67 clients exposed to one or both stylists and evaluated for COVID-19, none tested positive.
While fabric face liners are not 100% effective, “wearing them means you are exposed to fewer viruses. Other people get in less and are inhaling less. It is beneficial to everyone,” said Dr. John Brooks, a medical epidemiologist and the CDC medical director for the agency’s COVID-19 response.
If the American public accepted the masking now, Dr. Robert Redfield, director of the Centers for Disease Control and Prevention, said the pandemic could be launched in less than two months.
“If we could get everyone to wear a mask right now, I really think about the next 4-6-8 weeks, I really think we can get this under control,” he said in an interview Tuesday with the editor in chief of the Journal of the American Medical Association.
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Masks could mean getting sick less
And it could do more than calm the outbreak. One hypothesis among some infectious disease experts is that people infected while wearing masks breathe in a lower dose of the virus and, as a result, often have less severe disease.
An upcoming article in the Journal of General Internal Medicine presents the theory.
It makes perfect sense, said Dr. Joshua Sharfstein, a health policy expert at the Johns Hopkins Bloomberg School of Public Health.
“Wearing a mask can protect the wearer of the mask more than we think,” he said. “This document provides a new explanation for the lower death rates in areas where mask use is common, as well as an even stronger justification for all of us. Wear masks when you are around others.”
The reason is based on the medical concept of “viral inoculum,” or the amount of virus that someone is exposed to. Evidence for viral, bacterial, or fungal exposure affecting someone’s disease dates back to the 1930s.
“We know this for gastrointestinal viruses, sexually transmitted diseases, and respiratory infections. The higher the load, the more it enters your system, the more severe the disease, “said Dr. Monica Gandhi, a professor of medicine and an expert in infectious diseases at the University of California, San Francisco and co-author of the article.
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Using a cloth face covering is estimated to remove 65% to 85% of viral particles, said Dr. Chris Beyrer, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health and another author.
Depending on how robust the person’s immune system is, a lower exposure seems to correlate with milder cases of COVID-19. It’s probably because with a smaller amount of virus to deal with, the body’s immune system has a better chance of mounting a defense, the article authors suggest.
It is seen in many other diseases, said Otto Yang, professor of medicine and chief of infectious diseases at UCLA’s David Geffen School of Medicine.
“When someone is infected with a virus, there is immediately a race between the replicating virus and the immune system. The bigger a person’s inoculum, the bigger the advantage of the virus, ”he said.
It also appears that people who wear masks but who contract the disease are much more likely to be asymptomatic, which means they have COVID-19 but have no symptoms.
“If you are going to get this virus, you want to have an asymptomatic infection. As many surviving people have said, it is not a common flu. People are very sick, even those who do not require hospitalization.” Beyrer said.
The idea remains a hypothesis because scientists have no specific data, since human studies are impossible.
“We cannot spray the SARS-CoV-2 virus on people’s faces at lower and lower doses and see who gets sick,” said Gandhi.
But there is animal data. A study in hamsters found that if masks were used to filter the air in their cages, hamsters were less likely to become infected with COVID-19, and if infected, they had milder disease.
There is also ecological evidence of the pandemic that seems to confirm this. Take the case of two cruise ships that had COVID-19 on board.
“Cruises are somehow like a natural experiment,” said Beyrer. “Things were done differently on different ships and the results were different.
The first was Princess Diamond, where 18% of those infected with COVID-19 were asymptomatic. Very few passengers wore masks.
A subsequent infection hit another cruiser, the Shackleton. When the first case appeared, all passengers received surgical masks, and all staff wore N-95 masks. While 58% of the passengers and crew ended up infected with COVID-19, 81% of them were asymptomatic.
Another example comes from Oregon, where everyone who works at a fish processing plant receives masks every day at work. While 33% of the evaluated workers ended up being positive for COVID-19, 95% of them were asymptomatic.
In countries where a high percentage of the population wears masks, the number of cases may increase, but the number of deaths decreases. Some models show that if 80% of people wear masks, COVID-19 death rates remain very low.
In the United States, San Francisco has a very high level of mask use, and although cases have increased, the death rate has remained stable. In fact, there have been no new deaths since June 27. The city also shows a high level of asymptomatic cases.
A high level of asymptomatic cases means that fewer people actually get sick from COVID-19, and those who are less likely to spread the disease.
Face masks could be key to getting back to normal as possible before a vaccine is available. It will still require social distancing and handwashing, but masking could allow things to open up, the CDC Brooks said.
“What we are saying is that if everyone adopts fabric face covers, we can start socializing again without shutting down the economy,” he said.
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This article originally appeared on USA TODAY: Wearing a mask not only protects others from COVID, it also protects you from infection, perhaps serious illness.
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