Thread by @DrZoeHyde

(1/15) Study describing a probable case of #SARSCoV2 transmission by an asymptomatic person (completely without symptoms during infection) on an aeroplane during an evacuation flight to South Korea. #COVID19
wwwnc.cdc.gov/eid/article/26…

(2/15) This study included 310 people who boarded an evacuation flight from Italy to South Korea in March. Before boarding, 11 symptomatic people were identified, and removed from the flight.

(3/15) The remaining 299 people boarded. They were issued with N95 respirators, and sat 2m apart. Most passengers wore the N95 masks, except at mealtimes and when using the toilet.

(4/15) On arrival in South Korea, all individuals were quarantined for 2 weeks at a government facility. During this time they were completely isolated from one another, and were tested on day 1 and day 14.

(5/15) On day 1, a total of 6 positive cases were identified and transferred to hospital for observation. These patients developed no symptoms during 14 days, and were categorised as asymptomatic cases.

(6/15) On day 14, a previously healthy 28-year-old woman tested positive. She had worn a N95 mask on the flight, except when she used the toilet. She sat 3 rows away from one of the asymptomatic cases on the plane, and used the same toilet as this person.

(7/15) She developed symptoms on day 8 of quarantine and was transferred to hospital on day 14 after testing positive. The remaining 292 passengers were released from quarantine on day 15.

(8/15) All crew members and medical staff on the plane were also tested and quarantined for 2 weeks. None tested positive.

(9/15) The woman who tested positive in quarantine had self-isolated for 3 weeks before boarding the plane, and did not take public transport to the airport. It is therefore likely she was infected via indirect contact with an asymptomatic case.

(10/15) A similar case of presumed asymptomatic transmission also occurred on another evacuation flight to South Korea in April.

(11/15) On the second flight, 3 asymptomatic cases were identified. One person subsequently tested negative on day 1, but positive on day 14.

(12/15) The authors concluded that the woman on the first flight likely "became infected by an asymptomatic but infected passenger while using an onboard toilet."

(13/15) However, "[o]ther, less likely, explanations for the transmission are previous SARS-CoV-2 exposure, longer incubation period, and other unevaluated situations" and can't be definitively ruled out.

(14/15) The authors recommend that masks be worn on aeroplanes, physical distancing maintained, and that hand hygiene is necessary to prevent infection.

(15/15) Importantly, this study suggests that people with asymptomatic infection can transmit #SARSCoV2 (not merely those who are pre-symptomatic, as is already known). However, how common this might be remains uncertain.

This study might be of interest to you, @EricTopol.

@threadreaderapp unroll this thread, please.

Here's the unroll:

Study describing a probable case of #SARSCoV2 transmission by an asymptomatic person (completely without symptoms during infection) on an aeroplane during an evacuation flight to South Korea. #COVID19
threadreaderapp.com/thread/1297073…