COVID transmission by talking (& singing)

TL;DR: This is an ar­gu­ment that (1) Talk­ing is a ma­jor way that COVID-19 trans­mits from per­son to per­son (at least when peo­ple aren’t wear­ing face­masks and gog­gles, and pos­si­bly to a much lesser ex­tent even if they are), right up there with cough­ing, and prob­a­bly more im­por­tant than touch­ing con­tam­i­nated sur­faces; (2) The pub­lic is not gen­er­ally aware of this, at least where I am; plus (3) Sketchy ideas for what to do about it.

Epistemic sta­tus: Low con­fi­dence, open to crit­i­cism.

Back­ground: Why think that talk­ing (at least with­out face­masks) is a ma­jor trans­mis­sion risk?

  • This NIH video shows how talk­ing cre­ates droplets and aerosols, just like cough­ing does, and strongly ad­vo­cates that ev­ery­one should avoid face-to-face con­ver­sa­tions. They also made a fol­low-up video show­ing that face­masks help, even the kind of DIY face­mask made from old T-shirts.

  • This CDC web­page em­pha­sizes res­pi­ra­tory droplets and avoid­ing close prox­im­ity, adding that “con­tam­i­nated sur­faces or ob­jects … [are] not thought to be the main way the virus spreads.” The Chi­nese gov­ern­ment guide con­curs.

  • This ar­ti­cle by a do­main ex­pert ar­gues that the main way peo­ple catch it is prob­a­bly if some­one is talk­ing or cough­ing nearby, and agrees with the CDC that touch­ing con­tam­i­nated sur­faces is prob­a­bly less of a big deal, albeit with con­sid­er­able un­cer­tainty from the lack of data.

    • (She gets re­ally pedan­tic in ar­gu­ing that we should use the ter­minol­ogy “short-range aerosols” for what’s go­ing on, while the CDC, WHO, and ev­ery­one else seems to call the same thing “in­haled droplets”. I re­ally don’t care about the ter­minol­ogy. Every­one agrees about what’s go­ing on. But to be clear, the term “aerosol” usu­ally refers to long-range aerosol trans­mis­sion, like measles, and there seems to be a con­sen­sus that this type of tra­di­tional long-range aerosol trans­mis­sion is not a ma­jor part of COVID-19 trans­mis­sion, for rea­sons dis­cussed here, in­clud­ing ob­ser­va­tions about who catches it from whom. (ETA: ok, maybe the word “con­sen­sus” is too strong, see here.)

  • As jim­ran­domh and oth­ers have ar­gued, there is a lot of asymp­tomatic trans­mis­sion—so it’s not just peo­ple cough­ing.

Su­per-spreader events seem to in­volve singing in­doors and/​or face-to-face conversations

Two known COVID-19 su­per-spreader events may have in­volved the in­fected per­son singing in­doors for an ex­tended pe­riod:

First, the Sk­agit Valley Cho­rale case:

...The virus has dev­as­tated the Sk­agit Valley Cho­rale, based in the ru­ral valley north of Seat­tle… Of the 60 peo­ple who at­tended a March 10 prac­tice, 45 have de­vel­oped symp­toms and 27 so far have tested pos­i­tive, offi­cials said. One of the group’s mem­bers has died, an­other has been hos­pi­tal­ized and oth­ers have strug­gled to over­come their ill­ness.

Ruth Back­lund, a co-pres­i­dent at the Sk­agit Valley Cho­rale, said the group was mon­i­tor­ing pub­lic health guidelines at the time of the prac­tice and had asked peo­ple to stay home if they showed even minor signs of ill­ness. The group gath­ered in rows fac­ing a pi­ano and a choir di­rec­tor. They were all in in­di­vi­d­ual chairs and had space to keep sep­a­rated. Ms. Back­lund had made sure there were ex­tra soap dis­pensers in the bath­rooms for peo­ple to wash their hands.

“No­body was sick. No­body touched any­body. No­body shook hands. No­body hugged ev­ery­body like you might do in a group. There was none of that,” Ms. Back­lund said.

Se­cond, maybe the case of the Shin­cheonji re­li­gious sect in South Korea. I don’t know the de­tails, but in gen­eral, “At­ten­dants re­main seated on their knees through­out the ser­vice, chant­ing Amen and singing en mass”.

Other su­per-spreader events seem to be con­sis­tent with face-to-face con­ver­sa­tions with asymp­tomatic in­di­vi­d­u­als:

The Con­necti­cut party pre­sum­ably in­volved face-to-face con­ver­sa­tions, though it seems that few de­tails have been pub­lished. The in­fected per­son is said to have been asymp­tomatic.

The Bos­ton Bio­gen Con­fer­ence in­volved peo­ple mil­ling around with hors d’oeu­vres and drinks—again, pre­sum­ably con­sis­tent with spread by face-to-face con­ver­sa­tion. It seems that no­body was cough­ing there, though I could be wrong.

What can we do?

I think pub­lic health mes­sag­ing has not got­ten through about this. I pro­pose a motto /​ meme:

When some­one talks to you, they’re spit­ting on your face!

This mes­sage would help peo­ple un­der­stand viscer­ally why they’re be­ing asked to stay 2 me­ters apart. It would also help peo­ple un­der­stand viscer­ally why peo­ple are tel­ling them to make and wear DIY face­masks & gog­gles. (I just made my­self a mask yes­ter­day!)

Beyond that, aware­ness by it­self would be re­ally valuable in di­rect­ing peo­ple’s de­ci­sions and ac­tions. For ex­am­ple, where I live (USA), many of my lo­cal busi­nesses (gro­cery stores, take-out restau­rants, etc.) are go­ing above and be­yond in fre­quently san­i­tiz­ing sur­faces, non-con­tact e-pay­ments, staff wash­ing hands and wear­ing clean gloves, etc. etc. … yet shop­ping there still in­volves a face-to-face con­ver­sa­tion with the sales­per­son (who does not have a mask)!!

I want ev­ery boss of ev­ery es­sen­tial busi­ness to tell their em­ploy­ees: Don’t try to start a face-to-face con­ver­sa­tion with your cowork­ers or cus­tomers (es­pe­cially with­out face­masks), it’s just as rude and reck­less as cough­ing on them, or push­ing them into a busy street. I want a cul­tural norm that says that if some­one tries to start a face-to-face con­ver­sa­tion, the other per­son is en­ti­tled to run away!

Again, I could be wrong al­to­gether … and if this is a mes­sage worth pro­mot­ing, I’m not sure how to get lots of celebri­ties etc. to say “When some­one talks to you, they’re spit­ting on your face!”, in­stead of “wash your hands” (which is still a good idea but ev­ery­one has already heard that a mil­lion times).