The CDC released their updated estimates for the efficacy of the 2012 - 2013 flu vaccine and while the overall number has not changed significantly (now estimated at 58% effective versus earlier estimates of 62%), it appears the vaccine has performed very poorly for people over the age of 65.
Based on the study results, the vaccine has been only 9% effective at preventing the strain of influenza which caused most illnesses this year (influenza A H3N2) in people older than 65. We have long known that the flu vaccine is not as effective in older adults as it is in younger people, but these numbers are still surprising. There was a high dose flu vaccine available this flu season which was supposed to be stronger and provide more protection for people in this age group, but no studies have been released to show whether or not it was more effective this season than other flu shots.
Researchers and CDC officials are saying this should not discourage older adults from getting the vaccine because the findings are still preliminary, the study group was fairly small and some protection is better than nothing. The flu and pneumonia (which is a common complication of the flu, especially in older adults) is one of the leading causes of death in the United States for this age group.
See the full Press Release from the CDC.