1/ Outbreak investigation: #covid19 super-spreading event on a bus in China.

This study in @JAMA_current is compelling.

They describe notable spread of #covid19 throughout a bus that had recirculating air via AC system.

Thread

https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2770172

2/ 2 buses were headed to a religious event in China

-24 out of 68 were infected in the bus that had a #covid19 case

-0 out of 60 in the bus that did not

The index case was *not* symptomatic during the bus ride-- he developed symptoms that night after returning from the event.

3/ What is notable is that the attack rate of those sitting close & far away from the index case in the bus were not significantly different (was still higher in those closer)

Aside from the person right next to index pt, only 1 other that was sitting near a window got infected.

4/
-7 people who were not on either bus were infected at the actual religious event-- all 7 had close contact w/ index case

-the event was largely outdoors, but no one was wearing masks at the event or in the bus (this happened in January)

So what do we make of all this?

5/ Transmission of #covid19 likely happens to diff degrees by many different sized droplets & airborne particles, & this likely varies in different environments.

In closed environments like this w/o air exchanges, the contribution of aerosol-based transmission is notable.

6/ Takeaways:
-keep your windows open whenever possible; it can't hurt, and it could help
-keep wearing masks ESP in closed indoor settings where transmission is highest
-as we head indoors for the winter, better ventilation and better masks are, IMO, going to be important

7/ We wrote about the need for better masks months ago @HarvardBiz @RanuDhillon @sri_srikrishna @beier_dbeier

Many have talked about ventilation @zeynep @jljcolorado @linseymarr @AliNouriPhD

Let's not make the same mistakes we did w/ masks in March. https://hbr.org/2020/06/we-need-better-masks

Including @j_g_allen in that ventilation group above as well— he has been a critical voice on this front

Cc @CaroMT @CarolineYLChen @B_resnick @ASlavitt @mccabe_caitlin @acsifferlin @LennyMBernstein @NoamLevey @bylenasun @lauriemcginley2 @amymaxmen @chrissyfarr @cshea4 @germanrlopez @powellnyt @carlzimmer @apoorva_nyc @selenasd @yayitsrob @PoliticsReid @elizabarclay