More on H1N1 after seasonal flu vaccination

We’ve blogged before about the as-yet-unpublished Canadian data suggesting that prior receipt of seasonal influenza vaccination may increase risk for nH1N1 infection. Now a case-control study is out in the BMJ that suggests just the opposite—a protective effect of the 2008-09 seasonal vaccine during the early days of nH1N1 emergence in Mexico City. This study should be viewed as preliminary, given the small numbers and the case-control design. I’ve still heard no word on when (and where) the Canadian data will be published.