Flu vaccine may not be effective for all seniors

Vaccines against influenza were found to be only "modestly" effective at protecting people 65 and older from the flu, according to an analysis of relevant studies done by the Cochrane Vaccines Field in Rome and published online Sept. 22 by The Lancet.

Combining data from 15 studies, the researchers found that vaccines with the inactivated flu virus did not afford protection against influenza-like illnesses, influenza or pneumonia among elderly people living in the community, but prevented up to 30% of hospitalizations for pneumonia.

Evaluating data from 29 studies, they found that among elderly people living in long-term-care facilities, inactivated vaccines prevented up to 42% of deaths caused by influenza and pneumonia.

A second study, also published online by The Lancet, found that resistance to drugs to treat the flu had increased by 12% since the mid-1990s. It was the first such study of resistance done in 10 years.

Researchers at the Centers for Disease Control and Prevention found increased resistance to adamantane derivatives, such as amantadine and rimantadine, which have been used to treat influenza A infections for more than 30 years.

The researchers did not test for resistance to newer drugs such as Tamiflu (oseltamivir) and Relenza (zanamivir). A representative from Roche Pharmaceuticals, which manufactures Tamiflu, said during a Capitol Hill symposium on Sept. 20 that 25 countries are currently stockpiling the product in the event of a pandemic flu outbreak. Roche recently donated 3 million doses of the vaccine to the World Health Organization.

The antiviral drugs are expected to play an important role in protecting the world's population should a pandemic strike, since a flu vaccine will probably not be available initially.

Note: This item originally appeared at http://www.ama-assn.org/amednews/2005/10/10/hlbf1010.htm.