In reply to this post, folks have asked:

Considering the flu shot this year is specifically not effective against what’s actually going around, why would you say that?

and:

So we have a hobby farm with lots of animals, we are out in all weather types, two high school kids, wife works in a hospital (non-med), I have both a full time job, and a part-time retail job. Our immune systems are on high alert at all times in this environment. If the Flu shot is not effective against this years strain, and mearly elevates ones immune system, does it elevate it differently then our normal germ dense environment? I’m asking as I haven’t had a flue shot in years, but the wife gets one every year. Yet neither of us has had the flu in longer than I can remember. We get the common colds, but no incidents of flu. Same goes for the kids.

Reply:

This year, the vaccine is not as effective.  As of this writing, the vaccine only covers about 50% of the flu viruses found in the US, instead of the typical 80-90%.

The vaccine is always a guess.  The flu virus has a predictable progression across the planet, starting in the Far East, then Europe, then here.  US vaccine makers look at the viruses in Europe and make a vaccine to cover these.

Unfortunately the flu virus is crafty, and mutates over time.  It mutates enough over the summer that an entirely new vaccine must be made; occasionally it mutates quickly enough that the viruses in Europe, are significantly different by the time they reach the US.

So this year, it mutated quickly.  Does that mean it’s not worth getting the shot?  We need to step to some technical details for that.

The immune system focuses on “epitopes”, which are portions of proteins, viruses, etc that it recognizes and can attach to. The body learns (in an incredibly complex mechanism, beyond the scope of this post) which are good, and which are bad, epitopes. Typically the body is exquisitely precise as to what it selects as bad; it can even distinguish “left handed” from “right handed” molecules (see here). When you get any disease, it identifies the bad stuff, makes antibodies to target the disease, and starts killing it. There is a time delay, which can prove disastrous, depending on the bug.

Vaccines provide the target, without the disease. Typically, a vaccine is a whole, killed virus. It provides dozens if not hundreds of epitopes for the immune system to target. Some of these epitopes are quite strong, and invoke a strong response from the immune system, some are weak. The flu virus has many weak epitopes, and a few strong ones. Being a clever little bugger, it mutates the strong epitopes on a frequent basis.

Yet even recognition of the weak epitopes is better than nothing. It allows your body to prepare some defense, even if weak. And that is a leg up on the virus.

Remember that the flu kills about 30,000 people in the US every year, on average. A bad year is about 45,000 people. That’s about the same number of people killed by car accidents in the US every year, yet far fewer folks complain about seat belts than the flu vaccine.

I post about it because I see, by definition, all the critically ill ones.  And it’s unpleasant to watch someone drowning in their own blood, while their family watches, crying. And it’s not just old folks, either.

So, the short answer to all of that is, yes, it doesn’t work as well, and yes, it’s probably still worth getting.