Risk of symptomatic COVID-19 due to aircraft transmission: a retrospective cohort study of contact-traced flights during England’s containment phase

Paula Blomquist*, Hikaru Bolt, Simon Packer, Ulf Schaefer, Steven Platt, Gavin Dabrera, Maya Gobin, Isabel Oliver

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Knowledge gaps remain regarding SARS-CoV-2 transmission on flights. We conducted a retrospective cohort study to estimate risk of acquiring symptomatic SARS-CoV-2 on aircraft, to inform contact tracing and infection control efforts. 

Methods: We identified co-passengers of infectious passengers on 18 England-bound flights from European cities up to 12/03/2020, using manifests received for contact tracing. Infectious passengers were laboratory-confirmed cases with symptom onset from 7 days before to 2 days after the flight. Possible aircraft-acquired cases were laboratory-confirmed with onset 3-14 days post-flight with no known non-flight exposure. Manifests was merged with the national case management dataset (identifying cases, onset dates, contact tracing status) and the national COVID-19 linelist. Contact tracing notes were reviewed to identify non-flight exposures. We calculated attack rates (ARs) among all co-passengers and within subgroups, including by distance from infectious cases and number of infectious cases on-board. 

Results: There were 55 infectious passengers and 2313 co-passengers, including 2221 flight-only contacts. Five possible aircraft-acquired cases were identified; ARs of 0.2% (95%CI 0.1-0.5) among all flight-only contacts and 3.8% (95%CI 1.3-10.6) among contact-traced flight-only contacts sat within a two-seat radius. The AR among 92 co-travellers with known non-flight exposure to infectious cases was 13.0% (95%CI 7.6%-21.4%). There were insufficient numbers to assess differences between subgroups. 

Conclusion: We conclude that risk of symptomatic COVID-19 due to transmission on short to medium-haul flights is low, and recommend prioritising contact-tracing of close contacts and co-travellers where resources are limited. Further research on risk on aircraft is encouraged.

Original languageEnglish
Pages (from-to)336-344
Number of pages9
JournalInfluenza and other Respiratory Viruses
Volume15
Issue number3
DOIs
Publication statusPublished - 1 Mar 2021

Bibliographical note

Publisher Copyright:
© 2021 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

  • Aircraft
  • COVID-19
  • Contact tracing
  • Epidemiology
  • SARS-CoV-2
  • Transmission

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