Unless you haven't been paying attention to the news, you know by now that this is an early and moderately bad flu season. By CDC's classification system, influenza is "widespread" in 48 of 50 states. Only Hawaii and Tennessee escape this highest category, and the latter because flu peaked early there.
The good news is that this year's flu vaccine is a pretty good match for the prevalent strains. H3N2 - the bug that's causing the most severe symptoms and (mostly pediatric and elderly) deaths - is responsible for as much as 75% of the cases. And a version of that is in this year's vaccine. Most of the Type B flu is Yamagata, and that too is in the vaccine. There are some new strains and non-vaccine old favorites floating around, but they account for a minority of the cases. So if you haven't gotten your flu vaccination, it isn't too late.
Here's more interesting news. There's been a good amount of research done in the last few years attempting to link exercise and fitness levels to vaccine efficacy. Typically an influenza vaccine doesn't eliminate the chance of getting the flu; rather it reduces the chance. It seems to work better in some than in others. The normal vaccine effectiveness rate is somewhere between 50% and 75%. This year they estimate the vaccine effectiveness at 62%, which is about average. If there's a way to improve that vaccine effectiveness - particularly in the more vulnerable populations like the elderly - well the recipe for that is something the scientific community is searching for. Already they've established that more fit people tend to have better immune systems, and better immune systems produce more antibodies to the vaccine antigens. But that doesn't help someone today who may or may not be in good shape.
So scientists at Iowa State University and University of Birmingham in England have been doing tests on whether exercise on the day of the shot makes a difference. There are many permutations that have been tested on both humans and laboratory animals. Some exercise was before, and some after vaccination. Some exercise was whole body, and some on the arm getting the vaccination. Different doses of exercise have been tried. The bottom line is that a "right dose" of exercise appears to increase the antibody response to the vaccination by as much as a factor of 2. Too little and too much exercise lessened the peak response. The hypothesized mechanisms for how this could happen vary. For instance there is a known inflammatory (and immune system activating) response to an exercised muscle. (That's one reason we get sore.) Exercise also will spread the vaccine antigen from the intramuscular injection site to the entire body in an efficient manner.
Moral of the story?
- If you haven't gotten your flu vaccine by now, get it. If you've already caught influenza, it still isn't too late. There are several circulating strains, and this year's vaccine is trivalent (H1N1, H3N2, B Yamagata).
- Don't be a Uechi weenie. A needle in the deltoid isn't going to kill you. Get your shot, and then go work out. At the very least, the released endorphins will make you feel better. At best, you may be maximizing the benefit of the immunization.
- For now, don't obsess about whether you should get the vaccination before or after exercise. Just do both on the same day. And as always, don't overdo it.