Surprising Human Immune Responses Could Lead to Better Flu Vaccines
▻http://www.wired.com/2014/11/antibody-landscape-flu-vaccine
... when influenza infects someone, it not only triggers an immune response for that particular strain, but for all the strains of that type of flu that have ever infected the person. This phenomenon, named ‘back-boosting,’ means that our old immunity gets boosted every time we’re faced with a new flu virus. Typically, the back boost response was stronger for past strains that were closely related to the infecting strain.
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This means scientists can try to predict how the virus might mutate (an active area of research) and base a vaccine on that, without worrying about diminishing protection against current circulating strains