Editor’s note: This commentary is by Dr. Turner Osler, who is a career academic trauma surgeon at the University of Vermont Medical Center turned research epidemiologist.
Masks are among the oldest and most reliable medical technologies. They have been preventing infections in operating rooms for 150 years and were essential in battling the Spanish flu pandemic of 1918. But, amazingly, there’s still more to learn.
Masks effectively reduce the amount of virus broadcast by people shedding virus, and so masks protect those close to a (possibly asymptomatic) person shedding Covid-19. We know this because careful laboratory measurements of virus escaping from humans ill with a coronavirus similar to Covid-19 found that masks completely blocked detectable virus.
Although we can’t ethically expose humans to this virus, luckily, hamsters can catch Covid-19. This happy circumstance (for us, the hamsters not so much) allowed Yuen Kwok-yung to infect a cage of hamsters with Covid-19 and then test the transmission to an adjacent cage with a sheet of mask material between the cages. Infection transmission was reduced four-fold, showing that “masks” can make a big difference.
But masks also protect the wearer. Gandi observes that with Covid-19, as with all infectious diseases, dose matters. The minimum number of Covid-19 virus particles necessary to infect a human isn’t known, but it’s certainly between hundreds and thousands of particles. So, anything that reduces the number of viral particles reduces the risk of becoming ill. Moreover, even if illness does occur, reducing the inoculum of viral particles makes illness less severe. How do we know this? Well, our friends the hamsters were not only less likely to fall ill with Covid-19 when protected by mask material, but those hamsters who did become ill had milder cases of Covid-19.
A natural experiment involving two cruise ships, each of which was caught up in the pandemic, shows that masks reduce disease severity in people as well. On one ship masks were provided, but not on the other ship. Although just over half of patients eventually tested positive on the mask wearing ship, most (81%) were asymptomatic; on the ship without masks only 20% of Covid-19 cases were asymptomatic. Thus, severity of Covid-19 was greatly reduced in masked passengers, all the way down to asymptomatic for most of them.
Sometimes the best data is a story. Here are two: On Jan. 23 a person ill with Covid-19 went to a crowded restaurant in Guangzhou with several friends for lunch. No one wore masks and within days, 10 people developed Covid-19 (Lu et al. Emerging Infectious Disease, July 2020). By coincidence, on the same day a traveler with Covid-19 and a dry cough boarded an airplane in Wuhan along with 350 other travelers for the 14-hour flight to Toronto. Fortunately, he was wearing a mask, and none of his fellow passengers developed Covid-19. These are just two case reports, of course, but they tell a compelling tale: masks work.
The real strength of universal masking is simply that if everyone wears a mask a virus must penetrate not one but two masks to cause mischief. And remember, the goal isn’t to block every single viral particle, but only to reduce the number of viral particles below the infective dose; if a few thousand of viral particles make it through the two masks, disease won’t be transmitted.
So, masks are cheap, have no side effects, and are currently our most effective defense against Covid-19. And now they come in attractive colors and interesting patterns. How can we not love them? Or, at least, learn to love them?
The rise in “mask haters” seems puzzling. Yes, at first there were missteps in messaging by public health authorities who initially claimed only health care providers needed masks. This was unfortunate, and untrue, but has since been reversed. Perhaps more significantly, masks were seized upon as flags of tribal affiliation rather than tools of pandemic control, and this has proven much more difficult dynamic to walk back, perhaps because it became difficult to mask up without losing face.
The ease with which information, and especially misinformation, flows over the internet has worsened this problem. One can easily find articles on the web such as “Masks Likely Do Not Inhibit Viral Spread,” but these are just clickbait: this one turned out to be an entrepreneurial osteopath hoping to attract people to his online store in hopes of selling expensive dietary supplements.
It’s not always easy to recognize disinformation, but if something seems not to make sense, well, maybe it doesn’t. How could a mask hurt anyone? How could capturing sneezes not reduce viral spread? And, if in doubt, Dr. Anthony Fauci is a guy we’ve gotten to know through other pandemics, and we pay his salary. Tony has our interests at heart; other sources, perhaps not so much.
If everyone wore masks, this pandemic would recede across the country, reducing further deaths as we await a vaccine. Thousands of lives have been lost because we failed to embrace this simplest of technologies. It’s been heartbreaking for many families who won’t get a do over.
So, please, mask up to keep yourself, your loved ones, and all of us, safe.