How H1N1 Virus Spreads in an Airplane


Scientists have devised a mathematical model that can predict how H1N1 virus infections can spread in an airplane during a transatlantic flight. Depending on the length of the trip, one individual who has H1N1 could infect two to 17 people during an airplane trip.

One reason for the interest in how H1N1 spreads in an airplane is that air travel played a significant role in the spread of H1N1 from Mexico to other locations during the outbreak in spring 2009. This is the first study to investigate the importance of in-flight transmission of the virus.

Scientists from the University of California, Los Angeles, used the Wells-Riley equation, which is a standard for predicting the extent of outbreaks of infectious pathogens in buildings and other enclosed environments. The equation takes into consideration the number of people exposed, the respiratory rate of the person with the infection, the length of exposure to the infectious droplets, and the concentration of the virus particles over time.


The scientists used the equation to determine how many potential infections could occur during one transatlantic flight, given the presence of just one infected passenger on the plane. They found that if the infected person travels in economy class, two to five infections could occur during a five-hour flight, five to 10 during an 11-hour flight, and seven to 17 during a 17-hour flight.

Sally Blower, director of the Center for Biomedical Modeling at the Semel Institute for Neuroscience and Human Behavior at UCLA, noted that “We found that many infections could occur if the infected individual was traveling in economy class but relatively few if the individual as traveling in first class.” More infections occur in economy mainly because that class is much more crowded, and there is a higher probability that if a person with H1N1 is on an airplane, he or she will be in economy class.

Airplane passengers can take steps to help avoid infection with H1N1 and other infectious conditions while traveling. For example, it is important to stay hydrated, as dry mucous membranes make people more susceptible to microbial infection. Travelers should wipe their hands and the drop-down tray, arm rests, seat belt buckle, and other surfaces with alcohol wipes. While many people are self-conscious about wearing a facial mask, wearing gloves can be less obvious, although not as protective as a mask. Airplane passengers should also consider getting a flu shot or taking an antiviral. In addition, several recent studies have shown that Echinacea and vitamin D may be helpful in fighting flu.

Pleschka S et al. Virology Journal 2009 Nov 13; 6:197
University of California, Los Angeles news release, Jan. 6, 2010