Could Older Population Have Enough Exposure To Past H1N1 Flu Strains To Avoid Infection?

The point is that there is an ongoing competition between viruses and other living things. It's one of the reasons that looking at history through the lens of demography, genes and evolution can be so useful in figuring out why what happens, happens.

Could Older Population Have Enough Exposure To Past H1N1 Flu Strains To Avoid Infection?: "ScienceDaily (June 25, 2009) — A letter to the editor by Rhode Island Hospital infectious diseases specialist Leonard Mermel, DO, identifies characteristics of the outbreak of H1N1 in 1977 and speculates its impact on this pandemic.

Mermel notes that in the late 1970s, an influenza H1N1 reappeared in humans. It had a pandemic-like spread that began in younger aged individuals. This strain, known as the "Russian flu" H1N1, was similar to H1N1 strains that circulated internationally between 1946 and 1957. The Russian flu spread rapidly across the former Soviet Union, initially affecting individuals between the ages of 14 and 20 in schools, as well as young military personnel, and later spread to preschool children. Individuals older than age 30, however, had dramatically lower attack rates and the overall mortality was low. The epidemic peaked rapidly, with a relatively short duration.