I belong to the International Society for Infectious Diseases, or ISID, whose home page is www.isid.org. It is a consortium of physicians and public health workers who are interested in aspects of public health that are related to possible epidemics, among other things. Any worker can post a finding thru their ProMed-mail post, located at http://www.promedmail.org. In fact, it was a Dutch physician who had been working in China when the SARS pneumonia broke out who first announced it to the world when he returned to the Netherlands using this e-mail posting system. (Up to that point the Chinese government was minimizing the severity of the problem, in a replay of Ibsen's "Enemy of the People".)
There are discussions now posted in ProMED mail about the effectiveness of the present 3-strain flu vaccine in 2010-2011, with estimates of effectiveness ranging from 30% to 70%, and I refer you to their web site for further information.
These results should not be that surprising. There have already been two (U.S.) government studies showing that the efficacy of the current vaccine falls below protective levels after about 4 to 6 months. It therefore follows that the best protection would be to get a flu vaccine every six months, even though no insurance company or HMO or MCR will pay for it. There was an even more recent study demonstrating that a vaccine of four times the standard dose will provide satisfactory protection for one year.
I leave it to my readers to discuss these results with their primary care physicians. I myself plan to get a second flu shot six months after my last one, and pay for it of course. One caveat: we do not manufacture sufficient amounts of flu vaccine to give everyone in the U.S. two flu shots per year, and it is not clear what the government's response will be to requests for a second dose of flu vaccine.