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Main routes of covid-19 infection

I’ve been leaving this comment everywhere I can think of, because I’m impressed with this article by a reporter who looked at superspreader data very carefully. Jonathan Kay writing in Quillette.

The main groups of infection arise from places where people are in close proximity, indoors, and talking, laughing, singing loudly. That fits a pattern of mainly airborne infection by large droplets.

Being in close proximity for extended periods, such as members of the same household, is also very good at spreading it. But in terms of people you’re less close to, it seems to do best in enclosed areas where people are expelling air forcefully. The sport of curling, for instance, where the sweepers are practically nose-to-nose while working hard. That’s also why slaughterhouses are such a hotbed. Workers are inches away from each other, very noisy environment, and they have to shout to each other to do their work.

Not spread by aerosols (very small droplets) primarily, because then superspreading events would be in offices, on aircraft, and similar. New Zealand had a sort of natural experiment on that. One of their biggest clusters was centered on a flight attendant who worked on one of the usual nearly day-long flights before travelling to a wedding. The people on the planes he took did not get sick. People at the wedding did. (He was asymptomatic at the time.)

Also not primarily spread by touching surfaces, because then people like FedEx workers would be getting sick and being superspreaders. That’s not the pattern so far, either.

This isn’t to say you can’t get it via aerosol or surfaces. Just that those don’t look like the main routes.

It’s a fascinating article, quite long, well worth a read. The news-you-can-use part is that it means masks, any masks, even tea towels, plus distancing are the two most useful things to do when out and about.