To put it flatly, H3N2 is the problem child of seasonal flu.
It causes more deaths than the other influenza A virus, H1N1, as well as flu B viruses. It’s a quirky virus that seems, at every turn, to misbehave and make life miserable for the people who contract it, the scientists trying to keep an eye on it, and the drug companies struggling to produce an effective vaccine against it.
There’s long been a theory — and it appears to be gaining ground — that a person’s ability to fight off flu infections is based on their previous experiences with influenza. More specifically, their earliest experiences with flu. It’s thought that the first flu viruses that infect you leave an imprint on your immune system’s memory; if correct, the notion is that you’ll always be able to fight off viruses similar to your first flu foes better than you will other types of flu viruses.
“The biggest challenge or frustration is that H3 … for whatever reason, is the virus that we see causing the most severe illness in large numbers of people,” said [researcher Ed] Belongia. “And it’s also the virus for which our vaccine is least effective. And so that’s a double whammy that so far we have not been able to adequately deal with.”
Read full, original post: ‘The problem child of seasonal flu’: Beware this winter’s virus