Lecture 6: Modeling Influenza

Influenza causes more morbidity and mortality than all other respiratory diseases combined. There are annual seasonal epidemics that cause about 500,000 deaths worldwide each year. During the twentieth century there were three influenza pandemics. The WHO estimates that there were 40,000,000–50,000,000 deaths worldwide in the 1918 pandemic, 2,000,000 deaths worldwide in the 1957 pandemic, and 1, 000,000 deaths worldwide in the 1968 pandemic. There has been concern since 2005 that the H5N1 strain of avian influenza could develop into a strain that could be transmitted readily from human to human and develop into another pandemic, and it is widely believed that even if this does not occur, there is likely to be an influenza pandemic in the near future. More recently, the H1N1 strain of influenza did develop into a pandemic in 2009, but fortunately its case mortality rate was low, and this pandemic turned out to be much less serious than had been feared. This history has aroused considerable interest in both modeling the spread of influenza and comparing the results of possible management strategies.