The mask slows the spread of SARS-CoV-2 By reducing how much the infected people spray the virus into the surrounding environment when they cough or talk. Evidence from laboratory experiments, hospitals, and countries around the world shows that masks work, and that disease control and prevention centers in the U.S. Recommends face painting for the public. With all this evidence, mask-wearing has become commonplace in many places.
I am a doctor of infectious disease and a professor of medicine at the University of California, San Francisco. As governments and workplaces began recommending or ordering the wearing of masks, my colleagues and I noticed an interesting trend. Where most people wore masks, infected people were less likely to become seriously ill than those who wore fewer masks.
It seems that if people wear masks they get less sick.
When you wear a mask – even a cloth mask – when you don’t you will usually be exposed to a small amount of coronavirus. Both recent experiments using coronavirus and nearly a hundred years of viral research in animal models have shown that low viral doses usually mean less serious disease.
No mask is perfect, and wearing one won’t stop you from getting infected. But that could be the difference between a Covid-19 case that sends you to a hospital and a case so mild that you don’t even realize you’re infected.
Exposure dose determines the severity of the disease
When you inhale a respiratory virus, it begins to hijack any nearby cells to turn it into virus production machines. The immune system tries to stop this process to stop the spread of the virus.
The amount of virus you come in contact with – called a viral inoculum or dose – has a lot to do with how sick you get. If the exposure dose is too high, the immune response is drowned out. The virus takes a large number of cells and amidst the immune system’s strenuous efforts to contain the infection, the body suffers a lot of damage and the person can become very ill.
On the other hand, if the initial dose of the virus is low, the immune system will be able to contain the virus with less drastic measures. If this happens, the person experiences fewer symptoms, if any.
This concept of viral dosage related to the severity of the disease has been around for almost a century. Many animal studies have shown that the higher the amount of virus you give to an animal, the sicker it becomes. In 2015, researchers tested the concept in human volunteers using a non-lethal flu virus and found the same result. The higher the amount of flu virus given to volunteers, the more they became seekers.
In July, researchers published a paper showing that the viral dose is related to the severity of the disease in hamsters exposed to coronavirus. Hamsters who have been given higher viral doses have become sicker than those who have been given lower doses than hamsters.
Based on this research, it seems that if you have SARS-CoV. If -2 is approached, the lower the dose, the less sickness is obtained.
So what can a person do to reduce exposure doses?
The mask reduces the viral dose
Most infectious disease researchers and epidemiologists believe that coronavirus is spread mostly by airborne droplets and to some extent by small aerosols. Research shows that both cloth and surgical masks can block most particles that may contain SARS-Cavi-2. When a mask is not perfect, the goal is not to block out all the viruses, but only to reduce the amount you inhale. Almost any mask will successfully block a certain amount.
Laboratory experiments show that good cloth masks and surgical masks can prevent at least 80% of viral particles from entering your nose and mouth. Those particles and other impurities will get trapped in the fibers of the mask, so the CDC recommends that if possible wash the mask off your clothes after each use.
The final piece of experimental evidence that shows that the mask reduces the viral dose comes from another hamster experiment. The hamsters were divided into unmasked group and masked group by placing surgical mask material on the air intake pipes in the masked group cage. Husters infected with coronavirus were placed in a cage next to a masked and unmasked hamster, and air from the infected cage was placed into a cage with a non-protected hamster.
As expected, masked hamsters are less likely to be infected with Covid-19. But when some masked hamsters became infected, they contracted a milder disease than unmasked hamsters.
The mask increases the rate of asymptomatic cases
In July, the CDC estimated that about 40% of people infected with SARS-CoV-2 are asymptomatic, and many other studies have confirmed this number.
However, in places where everyone wears a mask, the rate of asymptomatic infection seems to be much higher. When an Australian Australian cruise ship named Greg Mortimer exploded in late March, passengers were given surgical masks and staff were given N95 masks after the first case of Covid-19 was identified. The use of masks was apparently very high, and although 128 of the 217 passengers and crew eventually tested positive for coronavirus, 81% of those infected remained asymmetrical.
More evidence Two recent outbreaks have occurred, the first of a seafood processing plant in Oregon and the second of a chicken processing plant in Arkansas. In both places, workers were provided with masks and were required to wear them at all times. With both plant outbreaks, about 95% of infected people were asymptomatic.
There is no doubt that wearing a universal mask slows down the spread of coronavirus. My colleagues and I believe that case studies such as laboratory experiments, cruise ship and food processing plant outbreaks and long-known biological principles make a strong case that also protects the mask wearer.
The goal of any tool to combat this epidemic is to slow the spread of the virus and save lives. Universal masking will do both.
This article was originally published by this talk Monica Gandhi At the University of California. Read the original article here.
