The Atlantic has a very nice article summarising the discussion of whether the flu vaccine prevents death among older people. The basic problem in evaluating interventions like these is self-selection, which can make "cohort studies" unreliable. Not really news to most economists, but it seemed to have created quite a fire storm among public health and MD researchers. A very worthwhile read.
Whether this season’s swine flu turns out to be deadly or mild, most experts agree that it’s only a matter of time before we’re hit by a truly devastating flu pandemic—one that might kill more people worldwide than have died of the plague and aids combined. In the U.S., the main lines of defense are pharmaceutical—vaccines and antiviral drugs to limit the spread of flu and prevent people from dying from it. Yet now some flu experts are challenging the medical orthodoxy and arguing that for those most in need of protection, flu shots and antiviral drugs may provide little to none. So where does that leave us if a bad pandemic strikes?