A little over a year ago, I was on a business trip to New York City. I was sitting in an airport lounge on my laptop reading about the latest in the world of science when I noticed a man in the next seat. His laptop was turned off and he was just staring at the screen. It was hard to tell if he was doing anything, but he was definitely watching something on his laptop. A few minutes later, I saw that strange icon from the Googles Earth app pop up on the man’s screen, and he entered the information into the browser window.
So how well did the Masks actually work against Covid-19? That’s a good question. To be honest, I’ll never know, as I never got to try out the Masks. After all, I had enough things to do in the final stretch of the game. To be fair, I should have saved the Masks for the final moments of the game. I might have even used them to trap the mutant and rescue my brother. Instead, I discovered the secret of its weakness and used the last of my ammo to finish off the creature. That was the last time I found anything interesting in the game. The rest of the experience was an exercise in slogging through a tedious story.
So How Well Did Masks Actually Work Against Covid-19?
by Gary Leff on June 27, 2021
Masks have been highly controversial and some of their biggest flash points have taken place on planes, from passengers getting ejected over not wearing them to the continued U.S. federal mask mandate for transportation when mask requirements are lifted in most other situations.
I argued that mask opponents should have been mask proponents, that they should have been touted as the conservative alternative to lockdowns. Though I also think the mask requirement on planes is no longer necessary.
So what do we actually know about the effectiveness of masks? First it’s important to separate out the ways that masks can help,
- Source control. Whether masks keep someone who is infected from spreading the virus
- Protection for the wearer. Whether masks keep someone who is wearing a mask from catching the virus
We rarely distinguish the types of masks for this analysis, although Lufthansa banned cloth masks and required KN95, KF94, or N95 masks. I have long written that if you were going to wear a mask you should get a decent one and learn to wear it properly.
We know that masks are highly effective against disease transmission in hospital settings, so why is it controversial elsewhere? People are using low quality masks and not wearing them properly so it’s not surprising that effectiveness would wane. Is this an argument against masks, or an argument for better masks?
There have been plenty of past studies on masks, showing their effectiveness and questioning their effectiveness. Many of these pre-dated the specific virus at issue, Covid-19, and many Covid-19 studies assumed transmission models such as respiratory droplets (that would be easier to stop than aerosols).
What’s really useful then is a new paper that does a fantastic job analyzizing data on Covid-19 transmission and mask–wearing to find that masks can reduce virus transmission by about 25% where there’s near-universal adoption, but that looking at where masks are mandated has little correlation with where high levels of mask-wearing takes place. Here’s a tweetstorm explaining the findings. (HT: Marginal Revolution)
Analyzing mask effectiveness is different than analyzing mask mandate effectiveness. And masks can help but they aren’t a magic bullet. This assumes the masks that people actually wear, not the potential effectiveness of using better masks, at least level 3 procedure masks if not N95s.
Just telling people they had to wear masks was a mistake. The policy focus should have been on supplying better masks and teaching people how to wear them effectively.
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