How could your history of influenza affect your body's response to vaccines?

If you have ever been vaccinated against the flu – and later in the same season, you were probably more than angry. Your doctor may have explained that the problem may have been that the flu shot was not appropriate that year for the strains that the person was coughing and sneezing in your direction.

But more and more influenza researchers offer another explanation: the problem, at least in part, could come from you.

More and more evidence suggests that sometimes our immune system simply does not follow the instructions a vaccine tries to give them – that is, make antibodies to fight against a given H3N2 or H1N1 virus. The reason? We all have an influenza background that determines how our immune system responds to both infections and vaccines.

"We have all been trained on different influenza viruses," said Scott Hensley, an badociate professor of microbiology at the University of Pennsylvania, who is studying the factors that influence influenza vaccine response.

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The idea is that the first flu viruses encountered by your immune system carry indelible marks. A person born in 1970 and whose first infection with influenza A was caused by an H3N2 virus will always have a better immune response to the H3N2 virus – or that part of the vaccine – than to a virus or to an H1N1 vaccine.

Read the full original message: Influenza science tells us another culprit when vaccines fail us