The director-general of the Chinese CDC has this to say: “The big mistake in the U.S. and Europe, in my opinion, is that people aren’t wearing masks. This virus is transmitted by droplets and close contact. Droplets play a very important role—you’ve got to wear a mask, because when you speak, there are always droplets coming out of your mouth. Many people have asymptomatic or presymptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others.” (https://www.sciencemag.org/news/2020/03/not-wearing-masks-protect-against-coronavirus-big-mistake-top-chinese-scientist-says) Yet, American public health officials and media are so focused on the shortage of N95 masks for healthcare workers that they’re missing a critical part of the solution to the coronavirus pandemic: mandatory public mask use.
You don’t have a mask? Make one! This has been done widely in Czechia (https://www.euronews.com/2020/03/24/coronavirus-czechs-facing-up-to-covid-19-crisis-by-making-masks-mandatory), and studies show that common materials such as dishtowels and t-shirts have up to 75% of the filtration efficacy of surgical masks, even for tiny particles far far smaller than respiratory droplets (https://smartairfilters.com/en/blog/diy-homemade-mask-protect-virus-coronavirus/). Wearing a homemade mask that captures even 60% of respiratory droplets means that the person wearing it may be 60% less contagious when out in public. It is a very, very cheap and obvious tool, used in almost all the countries that have shown success in combatting the virus.
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There are a lot of things that are not understood about the novel coronavirus, but we do know that it infects our respiratory system—the virus goes out the mouths and noses of those who are infected and into others’ mouths and noses to their lungs.
Researchers from the University of Hong Kong (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2843952/) counted respiratory droplets from people talking and coughing. They found that, in terms of respiratory droplet expulsion count, a person counting out loud from 1 to 100 is equivalent to a person coughing 20 times! If you measure total amount instead of number (since larger droplets probably contain more virus although they probably also travel less far), the total mass of droplets is only slightly less for the talker (10-20%). If you assume that it takes about 25 seconds for a person to count from 1 to 100, that means that a person IN TWO SECONDS OF TALKING spits out respiratory droplets in excess of ONE COUGH.
Washing hands, social distancing, and testing and isolation—ultimately, all of these measures come down to keeping infected people’s respiratory droplets from getting into uninfected people, or as few uninfected people as possible. They are all essential, but mandatory public mask use is also an essential tool in this toolkit.
- Washing hands – This is primarily useful because our hands touch “fomites,” such as handrails, doorknobs, etc., which have been contaminated by respiratory droplets. Even better would be keeping respiratory droplets off of potential fomites to begin with, and masks have the added advantage of keeping dirty hands away from faces.
- Social distancing – This is critical right now, but an extremely economically and socially costly method of prevention, especially with measures like “shelter-in-place.” Such drastic measures may be unavoidable in the near term, but clearly we can’t hide out forever. Consider the two meter distancing rule: It’s not that virus jumps 1.5 meters off of people’s clothes, it’s people’s mouths and the droplets they expel when they talk, that are the problem.
- Testing and isolation – A study on novel coronavirus viral load (https://www.nejm.org/doi/full/10.1056/NEJMc2001737) suggests that viral load is fairly high at the onset of symptoms and then goes a bit higher, perhaps peaking between 3 to 6 days later, before the body is able to fight down the infection (see graph below, annotations mine). Even if you assume that a person self-isolates starting the second day of symptoms, that leaves quite a bit of potential infectiousness (indicated in red below), during the asymptomatic and early symptomatic periods. With contact tracking and proactive testing the number of people infected during these periods can be reduced, but the bottom line is that there is no way that anyone can be sure that they are not currently infectious and shedding virus every time they open their mouth.
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Public health officials in America have spent a lot of time dissuading people from wearing masks because there is a shortage of medical-quality masks and they are afraid of hoarding by people who are less exposed than doctors or nurses. Of course, keeping frontline medical staff healthy is a first priority, but saying that masks do not work is deceitful and could bear a heavy cost when it comes time to convince people to wear them, which should be NOW.
Wearing even an N95 mask won’t GUARANTEE that you won’t CATCH the virus, but EVERYONE wearing a mask OF ANY KIND when in public would clearly have an effect on the amount of virus individuals drop while going about town, and thereby reduce the overall contagiousness of the disease. Given that people’s mouths are the primary vector, keeping them covered and keeping respiratory droplets from reaching other people and surfaces should have a significant effect on overall contagiousness.
Is it a magic bullet? No, but nothing is. Even with shelter-in-place, we have millions of people who have to go to work to keep trains running, prepare food, and deliver packages. Even if we tested EVERYONE, any test result would only be valid at the time the sample was taken, and no-one would really know for sure that they aren’t infectious even one day later. The solution to this problem is a combination of many half-measures. Universal mask-wearing in public is a nearly cost-less intervention that could offer just the margin of success that keeps COVID-19 from being a persistent rolling disaster.
I am writing this from Korea, where life has been turned down a few notches (theaters, gyms closed, street life down) but most people are still taking the subway and going to work. People are interacting with each other here—going to coffee shops and out to lunch, handling currency, sampling food at supermarkets. Although quarantine rules are getting stricter as international cases rise, the border also remains open to inbound travel. Yet new cases remain low. Testing and tracking has been key to this success, but it also shows that, once there is some stabilization in case numbers, we don’t have to stop living to fight this disease.
As public health officials have said, infection primarily happens in relatively close quarters. One of the clusters here is a call center—a crammed space where people spent a lot of time talking without masks on. If you think of other clusters—parties, conferences, churches, cruise ships, households—these are all situations where people are talking and dining (often at the same time) with a large number of other people, in possibly noisy settings with reduced personal space. Even if people only wore masks in such limited settings as well as workplaces and public transit, it could be enough to keep the disease from completely overwhelming us.
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America knew this in 1918 (a police officer is said to have shot someone for not wearing a mask in Boston, see https://www.theatlantic.com/ideas/archive/2020/03/how-fragmented-country-fights-pandemic/608284/), and Japan and East Asia somehow maintained this knowledge to the present, perhaps because of more recent recurrent outbreaks of infectious respiratory disease. Mask-wearing has always been about protecting society rather than the individual wearing the mask, but American public health officials and media are narrowly focused on it being not a 100% foolproof way to avoid illness. We need mandatory public mask use to help curb the pandemic.
Additional references:
https://www.sciencemag.org/news/2020/03/would-everyone-wearing-face-masks-help-us-slow-pandemic
https://www.washingtonpost.com/outlook/2020/03/28/masks-all-coronavirus/
