THREAD
1/ #Covid19 super-spreading event from a bar in Vietnam; this report is from a party for St Patrick's day in which one guest infected 12 others at a poorly ventilated crowded bar.

Genome sequencing analysis helped to confirm this.
https://wwwnc.cdc.gov/eid/article/27/1/20-3480_article
2/ They note that asymptomatic secondary spread occurred to people who were not at the bar as well.

Indoor, crowded, poorly ventilated spaces without masks are dangerous; these types of cluster spreading events are propagating this epidemic.
3/ While this may happen at bars, we have seen the same in others settings as well.

Sports games--> recent CDC report of an outbreak at a hockey game https://twitter.com/AbraarKaran/status/1318050866583228416?s=20
4/ We are well aware of the significant outbreak at an indoor call center in South Korea from earlier in the epidemic.

https://wwwnc.cdc.gov/eid/article/26/8/20-1274_article
5/ And of this outbreak from an indoor restaurant in China associated possibly with an air conditioning unit/ poor air exchange.

https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article
7/ We have seen a number of reports of transmission on airplanes as well; most if not all were in the era *before masks*! I have yet to see any large or small plane outbreak since universal masking on flights.

https://wwwnc.cdc.gov/eid/article/26/11/20-3299-f1

https://wwwnc.cdc.gov/eid/article/26/11/20-3254_article
10/ And in South Korea, we saw #covid19 outbreaks associated with high-intensity fitness/dance classes; we have seen others since then as well.

https://wwwnc.cdc.gov/eid/article/26/8/20-0633_article
12/ One that is particularly unfortunate is the wedding outbreak from the country of Jordan early in the epidemic, in which the father of the bride was the index case, had greeted most guests at the door; and propagated a super-spreading wedding.

https://wwwnc.cdc.gov/eid/article/26/9/20-1469_article
13/ Similarly we saw another more recent wedding outbreak from Maine, which led to subsequent outbreaks throughout the state, including in a jail. Again-- indoors, no masks, dancing, singing etc

https://www.npr.org/2020/09/16/913693778/how-1-maine-wedding-caused-hundreds-of-coronavirus-cases-and-7-deaths
14/ We all at this point remember #covid19 and ships/cruises.

Re-upping this CDC investigation of the Yokohama ship-- attack rates highest in more crowded cabins; asymptomatic spread-- the patterns repeat themselves.

https://wwwnc.cdc.gov/eid/article/26/11/20-1165_article
16/ Additionally, we had an outbreak in Boston over the summer at a hospital in which the break room was the location of spread where masks were removed to eat/rest etc; transmission can/will happen when we least expect it https://boston.cbslocal.com/2020/07/27/springfield-coronavirus-outbreak-bay-state-medical-center/
18/ This is all to say that there are very clear take-aways from all that we know; we know so much more now than we did in March or April.

And we are clearly headed into a third surge of #covid19 in the United States. https://twitter.com/AbraarKaran/status/1318061380113698826?s=20
19/ Learning from all of these past outbreaks:
-close/ prolonged indoor contact is high risk
-MASKS WORK!
-singing/dancing/high intensity activity--> likely more droplets and aerosols emitted + more inhalation--> more spread of disease
-Asymptomatic spread is very real
20/ This virus has many weak points.

It spreads largely through clusters in which few people infect many people and many people don't necessarily infect any people.

So if we can stop large outbreaks, we can drive transmission down.

This is a key part of #covid19 control.
21/ Addendum: Need to point out disproportionate impact on frontline workers that were forced to keep going without protection while we “stayed home”— here described outbreak at a meat processing plant— over 900 infections in 5 weeks (1 in 4 employees) https://www.cdc.gov/mmwr/volumes/69/wr/mm6931a2.htm
22/ And this.

Leaders talk a lot about protecting the vulnerable, but no $$ where their mouths are.

https://www.washingtonpost.com/national/osha-covid-meat-plant-fines/2020/09/13/1dca3e14-f395-11ea-bc45-e5d48ab44b9f_story.html
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