No, this has nothing to do with numerology, but instead has to do with the ways in which strains of flu change and imprint people over the years. This process has been going on forever although it has been thought to start with the H1N1 strain, so-called ‘Spanish flu’ that killed 10 million people in 1918. This strain hung around, infecting people, until about 1957. The effect that this had is that it imparted ‘childhood immunity’ on people and protects people born after 1968 from contracting certain other varieties of flu such as H7N9.

'Credit': https://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Influenza_A_-_late_passage.jpg/250px-Influenza_A_-_late_passage.jpg

When the flu virus infects you your bodies produce antibodies to fight the virus, after you have recovered from flu these antibodies stick around in your bloodstream and prevent you from contracting certain other, related, strains of flu in the future. So if the strains of flu for which you have childhood immunity, such as H1N1 or H2N2 are related to more modern strains of flu such as the H7N9 strain of bird flu then it provides immunity for this as well.

Michael Worobey, an expert in viral genetics at the University of Arizona found this startling link between birth year and the chances of infection in an effort to understand how to predict and prevent future pandemics. ‘It’s highly predictive’ Worobey said, in reference to the relation to year of birth, he also said that roughly ‘half the people are well-protected’ and the other half aren’t. This imprinting effect, therefore, isn’t a hard and fast guide to whether or not you’ll get flue but it is a good yardstick.

As for the sort of flu that you’re likely to contract this also depends on your year of birth. Whilst being born after 1968 does give you greater immunity against H7N9 and some others it provides less protection against H5N1, for this you need to have been born before 1968 and have gained the childhood immunity provided by H1N1.

The major conclusion drawn from the study is that roughly half the people are protected from a major outbreak of avian flu. Flu strains mutate all the time, as such people are advised to get a flu shot every year. However, minor pandemics do still break out, such as swine flu in 2009 and in order to better prevent this it will be necessary to better understand these imprinting effects.

By Sam Cottle