It sounds like astrology, but one of the world's most prestigious scientific journals has reported that the date of your birth determines which sorts of influenza you are most at risk of catching. The finding resolves a long-standing puzzle about the way flu outbreaks spread, and could help control future epidemics.
Flu infections are usually most dangerous for the elderly, the very young, or people with compromised immune systems. However, some outbreaks don't obey the rule. The H5N1 strain, for example, mostly affects the young, while H7N9 is a terror in retirement homes. The devastating effects of the 1918 to 1919 Spanish flu pandemic reflected the fact that most of those who died were young and middle-aged adults.
Explaining this troubles virologists racing to ready the world for what they see as an inevitable future outbreak. In the journal Science, a team led by Professor James Lloyd-Smith of UCLA have presented a possible answer.
The authors propose that there are similarities between apparently different strains of the virus, and that childhood infection by strain provides partial protection against strains that were previously seen as unrelated. People of a particular generation are likely to have encountered certain strains, and when they are exposed to a different, but somewhat related, virus, they are less likely to get very sick.
This sort of cross-protection is widely accepted, but Lloyd-Smith proposes that it applies to far more flu varieties than previously recognized, with all known versions of the virus being parts of groups where they protect against other members of that group.