As health experts urge the public to wear masks to slow the spread of the coronavirus, they continue to be rejected. Among the skeptics’ arguments: if the masks can’t fully protect me against COVID-19, what’s the point of using them?
The argument against scientists is that masks can help reduce the severity of the disease caused by the coronavirus, even if it becomes infected.
There is now mounting evidence that silent spreaders are responsible for most transmission of the coronavirus, making universal masking essential to delay the spread of the highly contagious virus, experts say.
This makes the coronavirus different from seasonal flu. With seasonal flu, the peak of infectivity occurs about a day after the onset of symptoms. But with the coronavirus, even among people who end up visibly getting sick, peak infectivity can occur before they show symptoms.
In fact, experts say, significant amounts of the virus can start to come out of people’s noses and mouths even when they feel good.
This is a key reason, they say, why tactics for dealing with the coronavirus must be markedly different than with seasonal flu. And the universal use of masks is key. Here’s a Q&A based on research and interviews with medical experts.
What’s the point of using a face cloth cover if you don’t filter everything?
Cloth face masks still provide an important protective benefit: They filter out most viral particles.
It turns out that that’s pretty important. Breathing a small amount of virus can cause illness or a milder infection. But inhaling a large volume of virus particles can cause serious illness or death.
That’s the argument of Dr. Monica Gandhi, professor of medicine at UC San Francisco and medical director of the HIV Clinic at Zuckerberg San Francisco General Hospital, about why, if infected with the virus, masking can still protect you from more serious diseases. disease.
“There is this theory that facial masking reduces the [amount of virus you get exposed to] and the severity of the disease, “said Gandhi, who is also director of the AIDS Research Center at UC San Francisco.
What evidence supports this theory?
The idea that a lower dose of virus means less serious disease is a widely used idea in medicine.
Even as early as 1938, there was a study that showed that by giving mice a higher dose of a deadly virus, mice were more likely to contract serious illness and die, Gandhi said.
The same principle applies to humans. A study published in 2015 gave healthy volunteers varying doses of a flu virus; Those who received higher doses became ill, with more coughing and shortness of breath, Gandhi said.
And another study suggested that the reason the second wave of the 1918-19 influenza pandemic was the deadliest in the US was due to overcrowded conditions in Army camps when World War I ended. . “In 1918, the army fields [were] characterized by a high number of people-to-people contacts and a high case fatality rate, sometimes 5 to 8 times higher than the case fatality rate among civilian communities, “the study said.
Finally, a study published in May found that surgical mask partitions significantly reduced coronavirus transmission among hamsters. And even if the hamsters protected by the mask partitions acquired the coronavirus, “they were more likely to contract very mild disease,” Gandhi said.
What if a city dramatically masks itself in public?
If Gandhi is right, it may mean that even if there is an increase in coronavirus infections in a city, the masks can limit the dose of virus that people are receiving and lead to less severe disease symptoms.
That’s what Gandhi says he suspects is happening in San Francisco, where wearing masks is relatively robust. More observations are needed, he said.
There is more evidence that masks can be protective, even when users become infected. She cited an outbreak at a seafood plant in Oregon where employees received masks, and 95% of those infected were asymptomatic.
Gandhi also cited the experience of those aboard a cruise ship traveling from Argentina to Antarctica in March when the coronavirus infected people on board, as documented in a recent study. The passengers obtained surgical masks; the crew obtained N95 masks.
But instead of about 40% of those infected being asymptomatic, which is what would normally be expected, 81% of those who tested positive were asymptomatic, and masks may have helped reduce the severity of illness in people. on board, Gandhi said.
What has happened in other countries where residents have masked themselves?
The protective effects are seen in countries where masks have been universally accepted for years, such as Taiwan, Thailand, South Korea, and Singapore.
“Everyone has seen cases when they opened … but no deaths,” Gandhi said.
The Czech Republic stepped forward to demand masks and issued an order in mid-March, Gandhi said; That’s about three months before Governor Gavin Newsom did it throughout the state of California.
But in the Czech Republic, “every time their cases increased … their death rate was totally flat. So they didn’t get serious disease with these cases.”
In May, the Czech Republic lifted its facial mask rule. “And they are doing very well,” Gandhi said.
