Your date of birth as well as the age of your first encounter with the flu would have an impact on your contamination with the virus throughout your life. This is the study carried out by researchers from the University of Arizona and California and published in Science which reveals it. Certain age groups suffer more than others from the flu.
Born before or after 1968, your “flu protection” differs
The research team studied two avian influenza A viruses, H5N1 and H7N9, which have already caused hundreds of cases of severe illness or death in humans. By analyzing data from all known cases of severe illness or death from flu caused by these two strains, researchers found that the strain of human flu a person was exposed to when they were first infected with the flu virus as a child determines which new strains of avian flu they will be protected against during a subsequent infection.
According to the study, the main difference would therefore be linked to your year of birth, and more precisely before or after 1968. As explained by Dr Gérald Kierzek : “People born before 1968 seem better protected against certain group 1 influenza viruses (H5N1, H1N1) but more vulnerable to group 2 viruses (H3N2, H7N9). It is the exact opposite for people born after 1968: they are better protected against group 2 viruses, and more vulnerable to group 1 viruses”.
This would be linked to a change in the HA (hemagglutinin) antigens of influenza viruses, which occurred in 1968.
The importance of age of first exposure to influenza
This “immunological imprinting” or “antigenic imprinting” effect appears to depend exclusively on the very first exposure to the influenza virus encountered in life – and difficult to reverse. The age of first contact with the virus would therefore have a significant impact on our future life. Indeed, according to Dr. Gérald Kierzek: “Antigenic imprinting suggests that the first exposure to an influenza virus in childhood, usually before the age of 5, leaves a permanent mark on our immune system..
Researchers use a simpler analogy to grasp: When a person is first exposed to the flu virus, the immune system produces antibodies targeting hemagglutinin, a lollipop-shaped receptor protein that protrudes from the surface of the virus. Like lollipops of different colors and flavors, flu viruses differ from each other in the parts that make up their hemagglutinins. But each of the 18 known hemagglutinin subtypes of the influenza A virus belongs to one of two main “flavor” groups.
“In this analogy, let’s say you were first exposed to an “orange lollipop” human flu when you were a child“Worobey said.”If later in life you encounter another subtype of flu virus, from a bird that your immune system has never seen before but whose proteins also have a similar “orange” flavor, your chances of dying are quite low due to cross-protection. But if you were first infected with a virus from the “blue lollipop” group as a child, it won’t protect you against this new “orange” strain.“.
Relative protection that does not replace vaccination
Remember, however, that there is no right or wrong year of birth to be susceptible to being infected with the flu. In all cases, it is necessary to get vaccinated if you are part of the groups at risk of complications and to remain vigilant in times of epidemic (barrier gestures, wearing a mask, washing your hands, etc.).
“This “protection” linked to the year of birth is not absolute and vaccination remains recommended, in particular for people at risk and elderly. With age, other underlying diseases make us vulnerable and the immune system weakens (immunsenescence)”concludes Dr Gérald Kierzek.