As people resume travelling, questions have been asked about how safe it is to fly on aeroplanes. However, better research is needed before airlines can respond with any certainty.

A Professor of statistics has calculated the risk of contracting COVID-19 while travelling on an aircraft in the US. The calculations are based on various assumptions such as the likelihood of an infected person being on a plane given the US local infection rates and the likelihood of face masks failing to contain the virus. He calculated that the baseline risk of catching COVID on a full flight was approximately 1 in 4,300. This was assessed to reduce by half to 1 in 7,700 if the middle seat in a bank of three seats was left free.

The study author openly acknowledges the limitations and assumptions used in the model. He aimed to give a rough approximation of the potential risks.

The findings reinforce the value of face coverings on aeroplanes and other forms of public transport.

As the author suggests, it also asks the question of whether the potential risk reduction is worth the economic cost of not filling one third of the seats. The question remains unanswered.

Where did the story come from?

The Independent newspaper reported on this study, which is available in a preliminary, pre-print form. As such it has not been peer-reviewed by experts. A single researcher modelled the risk.

What is the basis for the claim?

The study author estimated the risk that any passenger has of contracting COVID-19 infection during an aeroplane flight from three factors:

  1. The chances that an infected person is on the plane (based on the local infection rate at the plane’s origin and destination)
  2. The chances that compulsory use of face masks fail to stop COVID transmission
  3. The chances that one infected person passes on the infection to another at different distances apart

The author considered that this third factor will essentially depend on whether the airline has the policy of filling all seats compared with the middle seats left free.

They used data from the US Centers for Disease Control and Infection to look at the number of new infections in Texas and New York during one week in early July. They then assumed that people boarding a plane were either asymptomatic or had only mild symptoms of COVID-19. The author considered that such people are only half as infective as fully symptomatic people. They also assumed that those boarding a plane were less likely to have baseline risk factors for COVID-19 (e.g. being of higher socioeconomic status).

A previously published study has suggested that if everyone wears a mask, this reduces infection transmission from 17% to 3% – an 82% relative risk reduction. Another study had estimated that if people are in direct physical contact the infection risk is 13%, which then drops by about half for every metre people are further apart.

Using all of these assumptions, the study author calculated that the risk of contracting COVID-19 on a US domestic flight in early July was 1 in 4,300 if the flight was full. If the middle seats were kept free this risk was reduced to 1 in 7,700 – a 56% reduced risk.

The author acknowledges the limitations of this model. These include not accounting for whether or not people talk during the flight, or the risks incurred in the airport, during boarding or leaving the plane. There are also questions over the effect of the length of flight, or how the risk of sitting adjacent compares with that of people sitting in the rows directly behind or in front.

What do trusted sources say?

The UK government has issued advice for safer air travel, which includes advice to wear a face covering on-board. Face coverings are mandatory for flights within England and Scotland. However, the advice does not address the spacing of seated passengers on flights.

People are advised to:

  • Remain seated as much as possible
  • Follow instructions and guidance from the crew
  • Use contactless payment where possible
  • Be aware there is likely to be a reduced food and drink service
  • Make the cabin crew aware if you become ill

 

Analysis by EIU Healthcare, supported by Reckitt Benckiser

 

Citation

  1. Barnett A. Covid-19 Risk Among Airline Passengers: Should the Middle Seat Stay Empty? https://www.medrxiv.org/content/10.1101/2020.07.02.20143826v2.full.pdf (Accessed 20 July 2020)

 

Reading list

  1. Department of Transport. Coronavirus (COVID-19): safer air travel for passengers. https://www.gov.uk/guidance/coronavirus-covid-19-safer-air-travel-guidance-for-passengers (Accessed 20 July 2020)