A very clear, readable article about the effectiveness of masks lessening the frequency and severity of COVID-19 infections was written by Dr. Monica Gandhi, infectious disease specialist and faculty member of the University of California, San Francisco.
It appeared in the online publication Inverse and was entitled “Mask wearers are ‘dramatically less likely’ to get a severe case of COVID-19.”
She wrote, “In places where most people wore masks, those who did get infected seemed dramatically less likely to get severely ill. When you wear a mask — even a cloth mask — you typically are exposed to a lower dose of the virus than if you didn’t. Both experiments in animal models using coronavirus and nearly a hundred years of viral research show that lower viral doses usually mean less severe disease.”
The medical word for dose is inoculum (in-NOCK-you-lum).
This comes from inoculare, to graft something into something, and in our discussion it means getting viruses into us. The number of organisms to which you are exposed is a big factor in how sick you may become.
When the viruses get into your mouth, throat and lungs, they fasten to your cells, get inside and hijack host cells’ genetic machinery to make replicas of themselves. An infected cell ruptures, and the new viruses escape to infect other host cells.
Your immune system tries to stop this process to halt the viral spread. If the exposure dose is very high, your immune response can be overwhelmed, and its dramatic reaction can do a lot of damage to your body, making you quite sick.
However, if the dose is small, your immune system has a chance to contain the microbial rascals, and your reaction still permits your body to create a defense against that microbe.
A very real study was done in 2015 with human volunteers using a nonlethal flu virus strain. (Likely medical students who needed the money. Been there, done it.) The higher the flu dose given, the sicker they became.
In July, the same “dose response curve” test was done in hamsters with the SARS-CoV-2 virus, with the same results.
Dr. Gandhi wrote that all masks reduce the viral dose, not just the N-95 masks. Lab experiments have shown that 80% of airborne droplets, and to lesser extent, tiny aerosols, are blocked by cloth and surgical masks.
A tighter fit works better. Almost any mask will block some. A recent study in hamsters exposed to a viral dose behind a mask or in an open cage showed the same protective response. (If you think putting a mask on a little kid is tough, try a hamster!)
In July, the CDC estimated that about 40% of infected people had no symptoms. Both asymptomatic and minimally symptomatic infections in theory allow your immune system to build its defense without illness or damage.
Dr. Gandhi points out two real-life instances to illustrate masks’ value. One was on a now legendary Australian cruise ship with an outbreak where all passengers and staff were issued N-95 masks.
All were tested once on shore. The asymptomatic rate was 81%, compared to 20% on other unmasked cruises.
More evidence for masks’ benefits comes from a seafood processing plant in Oregon and a chicken processing plant in Arkansas. In both places, workers were provided masks and required to wear them at all times. In the outbreaks from both plants nearly 95% were asymptomatic.
In an academic version of her article in the Sept. 8 New England Journal of Medicine, Dr. Gandhi wrote almost the same information, but said, “universal facial masking might help reduce the severity of disease and ensure that a greater proportion of new infections are asymptomatic. … It could be a form of “variolation” that would generate immunity and thereby slow the spread of the virus as we await a vaccine.”
Variolation was used in variola or smallpox prevention prior to that vaccine. People who were susceptible to smallpox were inoculated with material from a skin blister of an infected person to try to cause mild infection and subsequent immunity.
Could you say this column unmasks the value of masks? Sure, they’re annoying as all get out, and fog up glasses, but if they free us from disease and misery, shouldn’t all of us capitulate and mask up?
Frank A. Bures is a semi-retired dermatologist in Winona.
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