# 1167
It is flu shot season, and this year we are reportedly awash in vaccine, as opposed to previous years. Here in the United States there will be more than 130 million doses available, when in previous years we were lucky to see 100 million.
Here in Florida, nearly every grocery store and drug store chain seems to be offering flu shots this year. No longer do you need a doctor's appointment, or have to line up at the Health Department.
I plan to get mine tomorrow.
That is the good news. The bad news is this year's flu shot may not be as protective as in years past. Here's why.
This year's vaccine will contain antigens for two Influenza A viruses (H1N1 & H3N2), and 1 Influenza B virus. The strain of H1N1 included is known as A/Solomon Islands /3/2006 while the H3N2 strain included is A/Wisconsin/67/2005. The B virus strain included comes from the B/Victoria/02/87 lineage.
Sampling over the summer, in the Southern Hemisphere, has shown that the H1N1 component is a good match to the limited number of H1N1 viruses tested.
The news isn't so good for the H3N2 viruses, of which only 18% sampled were a good match for this year's vaccine. Similarly, in a small number of samples taken, the B Virus component was only a match 1 out of 8 times.
It's a bit of a gamble each year whether the flu shot will be a good match or not. Decisions have to be made six months in advance as to which strains to include in this year's shot, and we generally can only accommodate 3.
In recent years we've seen both the H1N1 and the H3N2 strains circulate, and each has substrains that differ enough as to render a vaccine formulated on one strain less effective one formulated on another. This means we have more bases to cover with a vaccine, increasing the odds that we will miscalculate.
Over the summer, when it was Flu season south of the equator, we've watched a particularly nasty flu season develop. It is feared those virulent seasonal flu strains will move north of the equator over the next few months, and we will see a similar flu season.
Right now, we don't know which strain will dominate this flu season. If it is the H1N1, then we have reason to believe this year's shot will provide decent protection. If it is the H3N2 strain, or the B strain, then the shot may not confer nearly as much protection as we'd hoped.
So taking a shot this year is a gamble. But one with a very low cost. Flu shots are relatively inexpensive, and historically have been very safe.
This year, I'm thinking of my flu shot like chicken soup.
It may not help.
But it couldn't hurt.
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