"Importantly, we found that the number of infections that would occur on a flight was very dependent on which cabin the infected individual was sitting in," Blower said. "We found that many infections could occur if the infected individual was traveling in economy class but relatively few if the individual was traveling in first class."

So why do more infections occur in economy?

"Primarily, it's the more crowded conditions in economy," Coburn said. "And unfortunately, there is a very high probability - 75 percent - that if an infected person is on board, they will be in the economy cabin."

The researchers note that their results have important implications for understanding and predicting the global dissemination of H1N1, suggesting that air-travel restrictions may be useful in controlling influenza pandemics.

"Our results imply that one individual traveling by plane, by infecting other travelers on the same flight, could cause multiple simultaneous outbreaks in different geographic locations rather than causing only one outbreak," Wagner said. "For that reason, quarantining passengers who travel in economy class on long-haul flights could potentially be an important control strategy this winter, but there is no point quarantining passengers in first class."

Source: University of California - Los Angeles