What’s behind the mask (debate)?
Tom Frieden
President and CEO of Resolve to Save Lives. Former CDC director and NYC Health Commissioner. Focused on saving lives.
Masks have been an effective tool throughout the Covid pandemic, despite erroneous claims to the contrary.?
The widely cited Cochrane review on masks was poorly done and even more poorly communicated. Regrettably, researchers analyzed the wrong datasets, in the wrong way, and overstated their conclusions—leading to sweeping and inaccurate characterizations.
Many nuances around mask type, setting, behavior, and policy are explained in this helpful piece by Katelyn Jetelina. The CDC did an excellent review citing extensive evidence that masks are effective, from multiple studies. Vox also provided a good sense of some of the biases and inaccuracies in the Cochrane review and the idiosyncrasies of the lead author.
Although randomized controlled trials (RCTs) are extremely important, especially for many clinical questions, they are not the best method for every scientific question, as I outlined in NEJM several years ago.
The question of WHAT masks are being used for needs to be assessed. Where most transmission is in the household and masks aren’t worn in households, then they cannot be expected to prevent that transmission.
What also needs to be assessed isn’t whether a behavior is mandated, but whether it occurs. For example, mandates in an area already using masks at a high level of masking will provide limited incremental benefits, and mandates that are ignored of course don’t reduce spread.
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Different masks provide different levels of protection. And “two-way” masking (i.e., both on the person with Covid and the person being exposed) is much more effective than protective masking—it’s a form of source control. Better masks (N95 in particular) control much better.
The Cochraine review has glaring weaknesses, including limiting its scope to RCTs and inappropriately combining flu and Covid. Cochrane included only two actual studies of masking during the pandemic. The first, from Bangladesh, showed a marked reduction in infections. The second, from Denmark, suggested a 20% reduction but it had methodological problems and limited power to detect differences. I wrote about the errors in the flawed Denmark study in November 2020.
Given these shocking shortcomings, the only valid conclusion we can draw from Cochrane is that RCTs of masks in Covid found them to be slightly protective, that the absence of evidence is not evidence of absence and that many other studies with excellent methodologies show efficacy of masking is proportional to the quality of masks used, consistency of their use, and risk of Covid in the environments in which they are used.
Community-wide masking is associated with 10-80% reductions in infections and deaths, with higher numbers associated with higher levels of mask wearing in high-risk areas.
Bottom line: Masks work if they are worn in settings where Covid is spreading, and especially if they are higher quality, such as an N95 or KN95.
Resourceful world traveler specializing in high stress/risk environments
1 年When you say masks you mean real masks not some cloth? We’ve seen numerous studies and we also need to factor in how professionals wear masks and does hand hygiene vs karen soccer mom. My pediatric pulmonary spouse and myself being a former EMT and HazMat tech wore masks but we also washed our hands didn’t touch our face. Despite my aggressive traveling during covid as with all my colleagues in DHS bouncing around from riots to the campaign trails to international destinations I never got Covid (somehow influenza A twice lol). My issue is the ovef abundance of faith. People engaged in riskier behavior because “Oh I have a mask.” We saw this in my home state of Vermont. The mask mandate went into effect and we let tens of thousands of college kids on and we spiked radically with covid cases. We went from no cases for several months to swamping our system because people stoppee washing their hands and just assumed the mask would work 100% or close to it.
If masks are effective then why did China have to lockdown and effectively used force to keep people locked in apartment buildings in major cities for 12 weeks at a time on and off for close to 3 years? There is no country on earth with more stringent police enforced mask mandates then China and thus that's all the empirical evidence one should need that masking is very ineffective and actually puts those highest at risk under a false sense of security. If masks worked China would never have had to enforce rolling lockdowns. Japan is another country with prodigious societal masking, they blocked foreign incoming travel for 2 years and then when they allowed travel again in early 2022 covid cases skyrocketed in fact as high as USA peak covid cases per capita in 2022. There is absolutely no empirical evidence of any successful countrywide mitigation of covid transmission via the use of mask mandates. Show me a country where stringent mask mandates stopped covid transmission? We can have healthy debates but it wasn't masking in China and Japan, rather EARLY robust contact tracing, bans on foreign travel (for mostly island nations) months of quarantines etc that some countries bent the covid transmission curves not mask mandates.
Investor, entrepreneur, public policy, former U.S Chief Data Scientist
1 年??
Microbiologist
1 年Unfortunately the public was mislead in being told they wouldn't need them at first, then directed to wear ineffective cloth masks. Officials created the problem by not being very clear with information. If the supply had not been a problem, there would never have been a debate on effectiveness.