A recent article in the New England Journal of Medicine discussed various aspects of the Influenza immunization strategies.
The full article can be read here.
In summary, the current flu season in Australia has shown very poor protection from the current vaccine, with an estimated effectiveness of 10%. That is well below the usual 40-60% effectiveness that is more typical. The vaccine used in Australia is identical to the one being used currently in the United States.
Because the flu virus mutates readily, one cannot assume that our experience this winter will mirror that of Australia. The article discusses various technical issues that are involved. Those issues are thought to be related to the “low effectiveness” of last year’s flu vaccine.
Please see my article on Influenza for other ways to improve your immune response.