Infection risk: How many viruses and bacteria are transmitted in airplanes

Are passengers at increased risk of infection?

What is the probability of contracting infectious diseases such as influenza or SARS during a flight? American scientists recently looked into this question in a study funded by Boeing. The researchers found:

  • Despite many media reports, the exact transmission risks during a flight are largely unknown.
  • People who have fewer than two seats to the side and a row in front of and behind the infected person are at particularly high risk of infection.
  • Surfaces such as tray tables, seat belts and toilet handles can be carriers of viruses and bacteria.
  • Outside the one-meter area around an infected passenger, the risk of infection is only three percent.

With over 3 billion air passengers traveling annually, the transmission of infectious diseases through flights is an important global health problem. Air travel could serve as a channel for the rapid spread of infections and pandemics. Nevertheless, the exact risks are largely unknown. Researchers from the Nell Hodgson Woodruff School of Nursing and the Georgia Institute of Technology recently conducted a study on the likelihood of contracting an infectious disease while traveling by air. The study results were published in the specialist journal "PNAS".

How does a transfer take place?

According to the World Health Organization, the most important transmission routes for diseases such as influenza and SARS are airway droplets that are transported over short distances of less than one meter. If an infectious person sneezes, coughs, speaks, or even breathes, these droplets can be released. If the droplets get onto the conjunctiva or mucous membrane of a traveler or if they are inhaled, a transmission can take place.

Three possible transmission scenarios

A passenger can have close contact with infected people in three ways during a flight. They could either be in nearby seats, they could pass through sitting and moving infected people, or an infected person could walk past a sitting person.

The seat is crucial

The results of the study show that an infectious passenger with influenza or another droplet-borne infectious disease is unlikely to infect the other passengers if they are placed further to the side than two seats and a row in front of or behind the infected person. According to this, 11 to 13 fellow travelers around the infected are exposed to a particularly high risk of infection.

Transmission beyond the one meter range is unlikely

Outside the one-meter zone around the infected, the risk of infection is only around three percent according to the study results. However, these results only relate to the time you spend flying. The risk of infection in the queues at check-in or boarding was not taken into account. This could be a possible reason why the study results confirm that the likelihood of infection is lower than, for example, the WHO claims.

A model to calculate the likelihood of infection

A research team led by Vicki Hertzberg, a professor at the "Nell Hodgson Woodruff School" for nursing, and Howard Weiss, a professor at the Faculty of Mathematics at the "Georgia Institute of Technology", developed a model that measures the likelihood of infection taking into account the contact patterns between passengers and crew can determine.

Five round trips as the basis for the simulation

Data from five round trips from the US east coast to the US west coast served as the basis. The movements of passengers and crew were recorded. The researchers also collected air and surface samples from areas most likely to harbor microbes. This movement data was then transferred to thousands of simulated flight scenarios.

The flight behavior of the passengers

"We now know a lot about how passengers move on flights," Hertzberg explains in a press release on the study results. Around 40 percent of the passengers would never leave their seats, another 40 percent would only get up once during the flight. Only 20 percent of the passengers got up two or more times. Passengers who leave their seats are on average five minutes on the road.

Contaminated surfaces

The researchers also found that the transmission of pathogens is also possible via certain surfaces such as tray tables, seat belts and toilet handles. This can happen if a sick passenger coughs in his hand and later touches a toilet area or a luggage basket. "Passengers and flight crews can minimize this risk of indirect transmission through good hand hygiene," recommends Professor Weiss. You should also keep your hands away from your nose and eyes.

Data relate only to the plane stay

The study, which was carried out in collaboration with Boeing, only examined the possible spread of infectious agents within an aircraft. However, the transmission could also take place at other points on the trip, Weiss sums up. (vb)

Author and source information

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