Similar to unclear evidence of the efficacy of neuraminidase inhibitors due to incomplete data, there are questions about the efficacy of the flu vaccine.

The globalfamilydoctor.com website mentions that flu vaccine in the elderly has no benefit. "Insufficient evidence for the benefits of influenza vaccines in the elderly" This review contains 75 studies involving over 2.45 million participants http://www.globalfamilydoctor.com/search/GFDSearch.asp?itemNum=12159

And "Influenza vaccines don't benefit pediatric asthma patients" http://www.globalfamilydoctor.com/search/GFDSearch.asp?itemNum=12152

The Cochrane Database on "Vaccines for preventing influenza in healthy adults" according to McMasters concludes: "The review showed that reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies"

Further to a monetary skewing of data from the pharmaceutical industry, could it be that there is an institutional skew present as well?