Scientists have actually randomized people to wear N95 or regular surgical masks, then tracked how many people got infected with colds and flus similar to the coronavirus. This data can tell us whether N95 or surgical masks are more effective at preventing transmission of viruses. The results surprised me.
People’s Intuitions About N95 Masks and The Coronavirus
The results are surprising because I’ve seen several people claim that we need N95 masks to stop the coronavirus. They say surgical masks just won’t cut it when it comes to the coronavirus.



Coronavirus mask claim N95 surgical mask


Similarly, a doctor interviewed on CNN said that masks don’t work.

Coronavirus masks don't work


And to be honest, that’s my intuition too. N95 masks fit a lot tighter than surgical masks, and they capture a higher percentage of particles. They’re what I wear in Delhi and Beijing.



N95 masks prevent infection with viruses and PM2.5
The Surgical Mask vs. N95 Mask Test
Scientists tested this question by randomly assigning over 2,000 nurses to wear N95 or surgical masks. Then they tracked how many of them caught the flu.



Surgical masks prevent infection with viruses and PM2.5


I polled people on Twitter to see what people guessed. A majority (68%) guessed N95, so I’m not alone in my intuition.



N95 and surgical masks prevent infection with viruses and PM2.5


But when the data came back, it turned out that rates of infection were the same!



N95 and surgical masks prevent infection with viruses and PM2.5


Differences weren’t significant, although surgical mask users actually had slightly lower infection rates.

So,
We conclude that both types of masks can prevent the virus.


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