Low risk of transmission of influenza on the plane: 3.5% if sitting within 2 rows of infected passengers

This BMJ study assessed the risk of transmission of pandemic A/H1N1 2009 influenza (pandemic A/H1N1) from an infected high school group to other passengers on an airline flight and the effectiveness of screening and follow-up of exposed passengers.

The design was a retrospective cohort investigation using a questionnaire administered to passengers and laboratory investigation of those with symptoms.

The setting was in Auckland, New Zealand, with national and international follow-up of passengers. The participants were passengers seated in the rear section of a Boeing 747-400 long haul flight that arrived on 25 April 2009, including a group of 24 students and teachers and 97 (out of 102) other passengers in the same section of the plane who agreed to be interviewed.

9 members of the school group were laboratory confirmed cases of pandemic A/H1N1 infection and had symptoms during the flight. Two other passengers developed confirmed pandemic A/H1N1 infection. Their seating was within two rows of infected passengers, implying a risk of infection of about 3.5% for the 57 passengers in those rows.

A low but measurable risk of transmission of pandemic A/H1N1 exists during modern commercial air travel. This risk is concentrated close to infected passengers with symptoms.

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References:

Transmission of pandemic A/H1N1 2009 influenza on passenger aircraft: retrospective cohort study. BMJ 2010; 340:c2424 doi: 10.1136/bmj.c2424 (Published 21 May 2010).

Diagram of influenza virus nomenclature. Image source: Wikipedia, GNU Free Documentation License.