Infection risk How many viruses and bacteria are transmitted in airplanes

Passengers are at increased risk of infection?

What is the probability of getting infected with infectious diseases such as influenza or SARS during a flight? This question was recently addressed by American scientists in a Boeing-funded study. The researchers found out:

• Despite many media reports, the exact transmission risks during a flight are largely unknown.
• People who sit less than two seats at the side and a row in front of and behind the infected person are at particularly high risk of infection.
• Surfaces such as tabletops, seatbelts and toilet bowls can be potential carriers of viruses and bacteria.
• Outside the one-meter range around an infected passenger, the risk of infection is only three percent.

With more than 3 billion passengers a year, the transmission of infectious diseases through flights is a major global health problem. Air travel could serve as a conduit for the rapid spread of emerging 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 into the likelihood of contracting an infectious disease during a flight. The study results were published in the journal "PNAS".

According to a recent study, people are particularly affected by an increased risk of infection during a flight, sitting within one meter in the vicinity of the infected fellow travelers. (Image: m.mphoto / fotolia.com)

How does a transfer take place??

According to the World Health Organization, the major transmission pathways for diseases such as influenza and SARS are airway droplets that travel 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 reach or are inhaled on the conjunctiva or mucous membrane of a traveler, transmission may take place.

Three possible transmission scenarios

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

The seat is crucial

The results of the study show that an infectious passenger with an influenza or other droplet-borne infectious disease is unlikely to infect the other passengers if they are placed more laterally than two seats and one row in front of or behind the infected person. Accordingly, 11 to 13 passengers are exposed to the infected person a particularly high risk of infection.

Transmission outside the one-meter range is unlikely

Outside the one-meter zone around the infected, the risk of infection is according to the study results only about three percent. These results, however, only relate to the time spent during the flight. The risk of infection in the queues at check-in or during boarding were not taken into account. This could be a possible reason why the study results certify lower contagion probabilities than, for example, the WHO claims.

A model for calculating the probability 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 Department of Mathematics at the Georgia Institute of Technology, developed a model that estimates the likelihood of infection, taking into account contact patterns between passengers and crew members can determine.

Five round trips as a basis for the simulation

The data was based on five round trips from the US East Coast to the US West Coast. The movements of passengers and crew were recorded. In addition, researchers collected air and surface samples from areas most likely to harbor microbes. Subsequently, this motion data was 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. About 40 percent of 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 way.

Contaminated surfaces

The researchers also found that the transmission of pathogens is also possible on certain surfaces such as tabletops, seatbelts and toilet bowls. This could happen if a sick passenger coughs in his hand and later touches a toilet surface or a luggage basket. "Passengers and flight crews can minimize this risk of indirect transmission through good hand hygiene," recommends Professor Weiss. In addition, one should keep hands away from noses and eyes.

Data refers only to the aircraft stay

The study, conducted in collaboration with Boeing, examined only the possible spread of infectious agents within an aircraft. The transfer could, however, also take place at other points in the journey, Weiss concludes. (Vb)