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Meta-Analysis
. 2023 Feb 2;18(2):e0264294.
doi: 10.1371/journal.pone.0264294. eCollection 2023.

Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence

Anna C Rafferty  1   2 , Kelly Bofkin  3   4 , Whitney Hughes  3 , Sara Souter  3   4 , Ian Hosegood  3 , Robyn N Hall  2 , Luis Furuya-Kanamori  5 , Bette Liu  6 , Michael Drane  7 , Toby Regan  8 , Molly Halder  8 , Catherine Kelaher  2 , Martyn D Kirk  1   2
Affiliations
Meta-Analysis

Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence

Anna C Rafferty et al. PLoS One. .

Abstract

We critically appraised the literature regarding in-flight transmission of a range of respiratory infections to provide an evidence base for public health policies for contact tracing passengers, given the limited pathogen-specific data for SARS-CoV-2 currently available. Using PubMed, Web of Science, and other databases including preprints, we systematically reviewed evidence of in-flight transmission of infectious respiratory illnesses. A meta-analysis was conducted where total numbers of persons on board a specific flight was known, to calculate a pooled Attack Rate (AR) for a range of pathogens. The quality of the evidence provided was assessed using a bias assessment tool developed for in-flight transmission investigations of influenza which was modelled on the PRISMA statement and the Newcastle-Ottawa scale. We identified 103 publications detailing 165 flight investigations. Overall, 43.7% (72/165) of investigations provided evidence for in-flight transmission. H1N1 influenza A virus had the highest reported pooled attack rate per 100 persons (AR = 1.17), followed by SARS-CoV-2 (AR = 0.54) and SARS-CoV (AR = 0.32), Mycobacterium tuberculosis (TB, AR = 0.25), and measles virus (AR = 0.09). There was high heterogeneity in estimates between studies, except for TB. Of the 72 investigations that provided evidence for in-flight transmission, 27 investigations were assessed as having a high level of evidence, 23 as medium, and 22 as low. One third of the investigations that reported on proximity of cases showed transmission occurring beyond the 2x2 seating area. We suggest that for emerging pathogens, in the absence of pathogen-specific evidence, the 2x2 system should not be used for contact tracing. Instead, alternate contact tracing protocols and close contact definitions for enclosed areas, such as the same cabin on an aircraft or other forms of transport, should be considered as part of a whole of journey approach.

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Conflict of interest statement

Authors KB, WH, SS, IH, and MD have read the journal’s policy and the authors of this manuscript have the following competing interests: These authors are all employees of Australian and New Zealand airlines.

Figures

Fig 1
Fig 1. PRISMA 2009 flow diagram [22].
Fig 2
Fig 2. Forest plot showing weighted pooled attack rates for H1N1.
Fig 3
Fig 3. Forest plot showing weighted pooled attack rates for SARS-CoV-2.
See this image and copyright information in PMC

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