There apparently was a recent rumor causing quite a stir in some segments of the infectious diseases community that a paper was about to be published that would show that influenza vaccine doesn't work. Well, the
paper was published yesterday and the results don't quite match the rumor. Osterholm and colleagues have published a systematic review and meta-analysis on the efficacy and effectiveness of influenza vaccine in Lancet Infectious Diseases. The major finding was that the pooled efficacy of the vaccine is 59%. This is somewhat lower than that found by the Cochrane group (73% in years when the vaccine and circulating strains were well matched); however, there were some differences in methodology that are well outlined in an
editorial that accompanies the paper.
Shocking? I don't think so. I have never thought that influenza vaccine was a great vaccine. It's a good vaccine; certainly good enough to widely recommend its use. But clearly not so good as to
fire healthcare workers who refuse to take it.
Two years ago I
blogged about the interview in the Atlantic with Tom Jefferson, the head of the Cochrane influenza group. Here's the money quote from that interview:
"For a vaccine to reduce mortality by 50 percent and up to 90 percent in some studies means it has to prevent deaths not just from influenza, but also from falls, fires, heart disease, strokes, and car accidents. That's not a vaccine, that's a miracle."
I was impressed by the efficacy of LAIV (pooled efficacy 83% [69–91]) in children aged 6 months to 7 years. This should have been emphasized more in the press and in this blog. To protect grandma, vaccinate your kids!
ReplyDeleteTo explain why, I would point you to Mark Loeb's paper (JAMA. 2010 Mar 10;303(10):943-50.) that found a 61% herd immunity/efficacy of TIV for unvaccinated adults when children in their communities were vaccinated with TIV. I suspect this would be even higher if LAIV were used.
my original post: http://haicontroversies.blogspot.com/2010/03/herd-immunity-in-influenza.html