A more effective flu vaccine is needed for the elderly because of their diminished ability to fight off the illness and increased risk of dying from the infection, U.S. health authorities said.
The effectiveness of this year’s flu vaccine fell to 56 percent as of this month, down from 62 percent reported last month by the Centers for Disease Control and Prevention in Atlanta. The shot was least helpful in people 65 and older, who accounted for more than half of all flu-related hospitalizations, the most since the 2005 to 2006 flu season, as well as the largest number of deaths, the CDC reported today.
“The older you get, the less potent is your immune response,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in a telephone interview. “This is just a fact of physiological life in the immune system.”
In those 65 and older, the flu vaccine only offered 27 percent effectiveness, according to today’s report from the Atlanta-based CDC.
Flu and pneumonia were the cause of 9.1 percent of all deaths in the U.S. for the week ending Feb. 9, down from a high of 9.9 percent of all deaths the week ending Jan. 19. The peak of the flu season appears to be over in the south and east regions of the U.S., though the number of new cases has risen in the west, according to the CDC report.
The vaccine’s low effectiveness among elderly hasn’t prevented them from being the most highly vaccinated group in the country. According to the CDC report, 71 percent of people 65 and older were vaccinated as of last month. The CDC recommends vaccinations for all people older than 6 months.
“Better vaccines, especially for seniors, are needed,” the CDC said in a statement announcing the data.
There are several ways that flu vaccines could be improved for the elderly, Fauci said. The first is to increase the dose, boosting the immune response. That could mean a sorer injection site because of the larger amount of vaccine given, but with little other negative side effects.
The second is to add an adjuvant, a substance that boosts a vaccine’s potency, as is done in Europe. Some vaccines have aluminum salts or gels added to them, which stimulates a better response in the body. Vaccines for hepatitis and human papillomavirus, or HCV, contain adjuvants, according to the CDC.
The adjuvants can carry toxic side effects, though they are rare, and haven’t stopped their use overseas, Fauci said. “There have been some toxic side effects, though not very much at all because they’ve given tens of millions of times in Europe,” he said.
The third is to simply design better vaccines.
“Many of us in the field of infectious diseases feel we haven’t yet optimized the positive potential of the influenza vaccine as we have other vaccines,” Fauci said. That could mean better identifying strains of flu to put in the vaccine, or including more of them.
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