Last week, the CDC announced results showing that when dummy heads were fitted with a cloth mask over a surgical mask, or when a surgical mask had a knot tied near the corner of the mouth, more particulates were captured when the head emitted an aerosol from its plastic mouthpiece during a simulated cough than were captured by a surgical mask alone.
Headlines rang out:
I have no doubt the CDC's result is accurate. A cloth mask over a surgical mask is better than a surgical mask alone when a mannequin sprays aerosol from its mouth in a simulated cough. I would even wager that an additional mask will outperform just two masks in this test. Yet, I struggle to understand the value of the research question at this moment. This is not the research, nor the headline we need.
The Study Does Not Answer The Practical Question
Whether or not a cloth mask over a surgical mask catches more particulates when a dummy head simulates a cough is a theoretical question. The practical question is what actually happens when the CDC advises people to wear a cloth mask over a surgical mask?
The first step in answering this is to see what happens to a cloth mask over a surgical mask if worn by a human. For the purpose of this column, I (not a mannequin) tried double-masking. Fifteen minutes later, after I spoke to a few people, one mask was shielding my chin, and the other blocking my vision.
My point is simple: we don't know what the CDC's results mean when real people wear the mask in their daily life.
What Took So Long?
Nearly a year has passed since public health officials advised us to wear one mask. What took so long to study two? At least some researchers have access to dummy heads capable of generating aerosol from their plastic mouthpieces. Surely, one would test the double-masking strategy sooner?
And, I wonder, if two is good, why not three? If someone is planning a future mannequin study, do it fast!
Does the recommendation slow the spread of the virus?
Beyond the question of what happens when a real person double masks, there is a bigger question: what does advising people to double mask lead to? Does it slow viral spread?
We are a year into this pandemic and masks have become a polarized issue. Most , but some do not.
Among the folks who wear a mask, the vast , but only 15% do so when exercising outdoors. This result isn't surprising, as the World Health Organization advises against mask use when exercising.
Given this, whose behavior will double-masking change? Folks who don't mask aren't waiting for a new study showing that double masks decrease particulate dispersion to change their habits. Instead, I suspect that double masking is far more likely to increase the number of masks amongst the fraction of people who mask most seriously.
But, could the public message touting double masking somehow backfire? Might it lead the folks on the other end of the spectrum -- those who occasionally mask -- to become irritated by flip-flopping messages and omit single masking more often?
The bottom line is that this is an empirical question and the right way to settle it is with a massive cluster randomized trial. However, there is virtually zero chance of that happening, making the value of this recommendation at this moment uncertain.
It's Time To Think Beyond Only Masks
Masks are a visible symbol, and entire campaigns are targeted at getting folks to wear them. I have seen selfies posted online of folks who ran marathon-level distances with a cloth mask. I stand back in awe of them. I can't run that kind of distance even without a mask!
Masks have taken up all the oxygen in the room. Not literally -- research has proven that mask usage ; I mean it figuratively. Talking about masks has dominated the discourse about what we can do to stop COVID-19.
The mathematician Wes Pegden, who comments on COVID-19, made this observation:
The pandemic in a nutshell:
We have volumes of polling on whether Americans consistently wear masks "anytime they leave their house" but no regular surveillance on questions like "can you access paid sick leave", how many people fail to isolate when developing symptoms, and why.
— Wes Pegden (@WesPegden)
His point is well taken. We spend so much time thinking about masks, we have forgotten many other measures that might offer greater benefit in preventing the spread of COVID-19. If someone works as a cook, and they feel ill, can they afford to call in sick? One analysis finds that cooks have the of death during the pandemic.
Instead of wearing a cloth mask when running 20 miles outside, we might be better off using that energy to make sure the folks who prepare our food have access to N95-level masks and paid sick leave in case they fall ill.
Double Masks Are a Double Distraction
The data on double-masking are not drawn from real-world usage, and the recommendation may affect only a handful of people who are at the lowest risk of having the virus. Spending time on this research question right now diverts attention from more pressing research questions that focus on the people -- often the most vulnerable -- who must continue to work in conditions that could be made safer.
Masks are a visible symbol. They allow us to feel good for doing our part to fight the coronavirus, and we can easily feel hate and antipathy towards folks who do not wear theirs. Double masking allows us to renew these emotions. But, ultimately, these emotions are not helpful.
Shame and blame are not how we build consensus and curb pandemics. Nearly a year into the pandemic, no dummy head study can save us.
The path forward necessitates resources for places at high risk of pandemic spread; reliable childcare for essential workers; paid sick leave; safe spaces to quarantine; rapid testing and results; vaccination with urgency; honest vaccine messaging; and harm reduction that moves human interactions to low-risk settings.
Double-masking is not the research nor the headline we needed.
is a hematologist-oncologist and associate professor of medicine at the University of California San Francisco, and author of . The views expressed above are his own and not his institution's.