Thread by @AbraarKaran

✈️THREAD✈️

1/
Outbreak of #covid19 on an 18 hour flight in September flying from Dubai to New Zealand now officially published

7 ultimately infected; 4 likely in flight, sitting within 4 rows of one another, 2 of them while reportedly wearing masks

2/ 5 out of the 7 had been tested **before the flight** and tested negative

2 didn’t report getting tested before the flight but are *not* thought to be the index cases (those who started the outbreak)

BUT Index case was tested **5 days** before the flight!

3/ I circled the days that index case *should have been tested* — 24-48 hours before flight, when they had likely started incubating the virus; when detection could have happened; when the outbreak could have been prevented

3/ 4 out of the 7 thought to be infected *on the flight*

Of those, 2 reported wearing masks during the flight and 2 did not

Why people would not mask during a flight in September is...really unclear to me.

Should have been mandatory but it wasn’t (!!)

4/ Two additional points

First, transmission could have happened before the flight but the passengers were interviewed and reported no close contact with each other before flight

Second, power unit of flight off for 30 mins during refueling in Malaysia so plane vents off(?)

5/ Many things to think about here

•index case only had a negative test from 5 days before the flight — if they had tested within 24-48 hours, presumably would have been caught

Airlines are *not* checking for this in the US (!!)

They recommend it. But that’s about it

6/ During the four transmission events in-flight, 2 were wearing masks and 2 were not (per their reports)

We know people remove masks to eat/drink on flights, so that is a possibility

Alternative is that cloth masks aren’t perfect; if they were wearing high filtration masks...

7/ ...could this have been prevented.

As you can see clearly here, many layers to stopping transmission!

⚠️Testing (wasn’t done correctly)

⚠️masking (inconsistent, not high filtration)

⚠️distancing (they were within 4 rows)

⚠️ventilation (when power unit was off)

✈️ outbreak- interesting Cc @j_g_allen @SaskiaPopescu @BhadeliaMD @syramadad @LauraSanthanam @celinegounder @lisalsong @jljcolorado @AliNouriPhD @johnbrownstein @DFisman @lmadoff @Cleavon_MD @carlzimmer @CarlosdelRio7 @MonicaGandhi9 @IngridKatzMD @kj_seung @EricTopol @NickKristof

✈️ #covid19 outbreak w/ more details Cc @rvenkayya @rajpanjabi @elizabarclay @B_resnick @acsifferlin @skarlamangla @kakape @LennyMBernstein @Laurie_Garrett @amymaxmen @germanrlopez @sciencecohen @apoorva_nyc @PoliticsReid

8/ My own personal take-away from this ✈️✈️ outbreak report is NOT that planes are extremely high risk— this example shows **how** transmission **can** happen, & why there are LAYERS to prevention & transmission!

As you can see here, MANY protocols were not followed! #covid19

9/ an older thread on how I’m thinking about flights — other #covid19 outbreak studies of flights were mostly before there was any masking on flights (although even on ⬆️ flight in September, masking not required...)

https://twitter.com/abraarkaran/status/1307347250465648643