[MD Expat in PA]

I'd think that you'd build up an immunity - at least to prior, existing variants of the flu - as you get a few years of shots under your belt. Obviously not to new strains and strains that aren't a part of the vaccinations, but why not to old ones? I can't imagine that your immune system "forgets" the vaccine every November.

Aside from there being several different strains of influenza, the virus which is an RNA virus) has a rather high rate of mutation. In the same way the common cold virus mutates and you can get sick from a cold (rhinovirus also a RNA virus) more than once during your lifetime.

It is thought that a flu shot can give you immunity or partial immunity for more than one year, perhaps two, but since it is a crap shoot each year which influenza strain(s) will be the most prevalent, it is recommended to get one each year.

[wbill]

Gotcha. Good info, I'd always wondered about that. The pat answer from my PA is "Get the shot.". Being a natural contrarian, I always ask "Why?". :-)

I always amazed at the wealth of real knowledge on FR.

Ultimately, it doesn't matter, now I get the shot. Had the flu a few years ago and thought that I was going to die from it. Would be foolish not to take basic preventative measures.