Some musings on flu shots...

It’s that time of year again, when we are collectively bombarded with relentless propaganda about the benefits of the flu shot. I don’t really want to debate whether or not you should get a flu shot, but there are some fringe stories that I find interesting…here I’ve found some interesting factoids that will make you sound smart at the pub!

Do it again. And again. And again.

Here’s an interesting statement: if you get a flu shot this year, then you will be worse off next year if you don’t get one. The theory goes like this… the immune system retains antibodies for diseases it has already fought in higher concentrations then background levels of random antibodies. By injecting you with a dead flu virus, flu-shot pushers are encouraging your immune system to create antibodies against that virus so that you are ready should you ever encounter the live version of the virus.

Let’s say your immune system develops four antibodies that are effective on one type of virus. Over the course of the winter, the virus mutates slightly, and you end up getting infected with a strain with only two binding sites in common with the one from the flu shot. The theory goes that your immune system will recognize the two sites on the virus that it has antibodies for, and produce more of these antibodies to fight the infection. In doing so it will ignore the newly evolved sites on the virus and stick with binding sites it recognizes.

Now let’s say next year, the virus has mutated some more, the two “new” sites on last year’s virus are still there, and maybe one of the old ones is still there as well. Because the antibodies for the old sites were effective when you were infected last year, the immune system didn’t make any antibodies for the new sites, and now the one antibody it still has for the old site is no longer enough to kill the virus, and you get sick!

Consider the alternative: last year you didn’t get a flu shot, and naturally fought it off by developing antibodies for all the sites. This year, you have antibodies for all the sites on the virus you contracted, and two of them still match up, allowing you to fight the infection. On the other hand, if you got a fresh flu shot next year, then it might have more antibodies that match the new ones. Is it believable? Maybe…. It depends on how fast it mutates.

Sunspots

This is an interesting story that you might not find elsewhere. Its especially interesting with all the media hype about bird flu slaughtering hundreds of millions. Well it turns out that there is an odd sort of correlation between sunspot cycles and flu pandemics. (What’s a sunspot?... click here). Check out the graph of flu pandemics and the sunspot cycle.

If this trend continues, with the next sunspot maximum expected to be in 2012, the next flu pandemic should be about one year prior. So my prophesy we’re all doomed in 2011. The more interesting question is why the correlation? Any ideas? Are higher levels of radiation during the sunspot peak causing more rapid mutation? Or is there some other explanation? I have heard a theory, but it’s complicated. If you care to hear it, I'll tell you sometime... it's not simple.

The Next Pandemic

So the next pandemic is expected to be bird flu H5N1. Will there be a vaccine against H5N1 by 2011? As of April this year, there already is! However, because of the rapid mutation of the influenza virus, even the current year's flu shot is not 100% effective for this year's flu. The lag time between outbreak and mass development of the flu shot can be up to 6 months. On a good year, the flu shot is only 80% effective, and for the current year it is only 40-50% effective. (See story here).

This makes it pretty much impossible to make a vaccine until an outbreak occurs. The vaccine against the bird flu that has been developed can only hope to slow it down until a custom tailored vaccine can be produced. Even then, it will have to be updated as the pandemic progresses to match the rapid mutation rate of the virus, making it logistically challenging to administer vaccinations worldwide. So relax… live for the moment. We could be dead soon.

Image Sources:

http://journalism.wlu.edu/rrarchive/11-17-2005/images/flu%20shot.jpg

Nature, 343, 25 January, 1990, p.304.

References:

Do it again next year: http://www.rice.edu/sallyport/2003/fall/sallyport/flu.html

Sunspots: http://www.nature.com/nature/journal/v275/n5676/pdf/275086a0.pdf

Bird Flu Vaccine: http://www.cdc.gov/flu/avian/gen-info/qa.htm