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Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 During Long Flight

Our take —

This was a contact tracing study conducted by the Vietnam Ministry of Health that examined a cluster of SARS-CoV-2 cases during a flight from London, UK to Hanoi, Vietnam. The overall attack rate on-board was 6.6% among passengers. Most of the secondary cases were located in business class where the index case was located. Though this article is relevant in providing useful information on how the virus can rapidly spread on airplanes, data on masks use or how people moved throughout the plane were not available, which makes it hard to determine the extent to which droplets, aerosols, or touching surfaces could have elevated transmission risk.

Study design

Cross-Sectional

Study population and setting

A cluster of SARS-CoV-2 cases occurred on a flight traveling from London, UK to Hanoi, Vietnam on March 2, 2020. Investigators conducted contact tracing among 211 passengers and 16 crew members onboard a 10-hour flight: flight VN54. Suspected flight-associated cases were passengers and crew that had cough or fever between March 1-16. Confirmed cases of SARS-CoV-2 were those who were PCR positive.

Summary of Main Findings

The index case went on flight VN54 on March 1 and was symptomatic (i.e. with a sore throat and cough) at the time of flight departure. All of 16 crew members and 84% (n=168) of passengers were successfully traced by March 10. Investigators found 15 (6.6%) confirmed flight-associated cases (14 passengers and 1 crew member). Of these cases, 12 were seated in business class with the index case, and two other passengers and crew member were in economy class. Ninety-two percent (11 passengers) among those seated within 2 seats of the index case in business class became infected, while 1 who was seated at least two seats away became infected. The median time to the onset of symptoms following arrival to Vietnam was 8.8 days.

Study Strengths

A strength of this study is that investigators were able to successfully trace most of the passengers and crew onboard the flight (~85%).

Limitations

Investigators were not able to confirm epidemiologic links through genomic sequencing data to confirm sources of transmission; however, given that most cases were in business class with the index case strongly suggests this was the source of transmission. They were also not able to document the presence of face masks or movements about the cabin, thus complicating claims of the route of transmission. 

Value added

As several countries are starting to loosen travel restrictions, this study provides evidence that suggests airplanes can be the site of super-spreader events.

This review was posted on: 20 October 2020