In that scientists have previously determined that contagious diseases including smallpox, measles, tuberculosis, seasonal influenza and severe acute respiratory syndrome (SARS) can be transmitted during commercial flights, Sally Blower, from University of California – Los Angeles (UCLA; USA), have completed a study that predicts the number of H1N1 flu infections that could occur during a flight could be fairly high.  Using novel mathematical modeling techniques to predict in-flight transmission of the H1N1 virus, the team found that transmission could be rather significant, particularly during long flights, if the infected individual travels in economy class. Specifically, 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.  They also predict that H1N1, even during long flights, poses a low to moderate within-flight transmission risk if the source case travels First Class.  The researchers explain that: "Primarily, it's the more crowded conditions in economy, [a]nd unfortunately, there is a very high probability – 75% - that if an infected person is on board, they will be in the economy cabin."