Flu and Herd Immunity

If you’re the sort of person who, like me, gets torqued about public health issues, there’s a important study out in JAMA today (.pdf here) about the population benefits of the seasonal flu vaccine; the upshot is that by vaccinating a little over 80 percent of kids between 3-15 years of age, researchers were able to observe a roughly 60 percent effectiveness at reducing influenza rates throughout the study population. The results themselves aren’t especially surprising — they affirm what everyone already suspected about seasonal flu vaccines and herd immunity, and they serve as a reminder that even a sub-optimal jab is quite effective at muting the spread an unpleasant illness that kills tens of thousands a year in the US alone — but the design of the study is really fascinating, as researchers were able to work with about fifty self-enclosed Hutterite colonies in central and western Canada, providing exactly the sort of controlled conditions that are usually beyond the reach of folks doing research on influenza vaccine efficacy. (It’s also interesting to note that the study utilized the killed virus vaccine, which usually proves less efficacious in flu studies than the weakened virus.)

I’d like to believe that the results of this study will embarrass the vaccine contrarians into prolonged silence, but I won’t be holding my breath. Since vaccination rates fall well short of the 80 percent threshold in the US, the market for uninformed skepticism won’t soon be disappearing. I’d also like to believe that studies like this would receive enough publicity to nudge parents away from Robert Sears’ nonsensical “alternative vaccination” schedule, which urges us (among other things) to avoid giving our kids seasonal flu shots until they’re five years old. Aside from demonstrating yet again that seasonal flu vaccines are perfectly safe for healthy children, the study offers the best evidence to date that flu vaccination is a socially responsible practice that benefits populations — especially the elderly — who tend not to respond vigorously to the serum. But as long as we can round up some asshole to claim that baking soda cures H1N1, there’s little risk that sensible ideas will prevail.