March 2 (UPI) -- Researchers found the high-dose flu vaccines may be more effective at preventing post-influenza deaths than the standard dose in seniors.
In a study of Medicare beneficiaries, researchers at the Centers for Disease Control and Prevention and the Food and Drug Administration found older adults given high-dose flu vaccines were better protected against influenza death than those receiving normal-dose vaccines.
Seniors are at higher risk for serious complications and death from the flu than young adults and middle-aged people -- between 71 percent and 85 percent of flu-related deaths occur among people over age 65.
"This is the population that everybody worries about," Dr. David K. Shay, a researcher in the CDC's Influenza Division, said in a press release. "Many of the most serious outcomes of flu infections occur in older people."
The high-dose flu vaccine was introduced and approved for adults 65 and older in 2009.
Researchers from the CDC, the FDA and the Centers for Medicare and Medicaid Services studied data from more than 1 million Medicare beneficiaries who received the high-dose or standard-dose flu vaccine in the 2012 to 2013 and 2013 to 2014 flu seasons.
Results showed that people who received the high-dose vaccine were 36 percent less likely to die in the 30 days following hospitalization or emergency room visit for the flu in 2012 to 2013 than those who received the standard-dose vaccine. The H3N2 flu virus, which is linked to higher mortality rates in seniors, was the predominant form of flu that season.
In the 2013 to 2014 flu season, H1N1 was the dominate virus at the time, the standard-dose vaccine had better effectiveness than the previous season. High-dose vaccine was not better at preventing deaths in patients studied during that flu season.
"The high dose vaccine does appear, at least in this particular H3N2 season, to be more effective at preventing deaths that occur within 30 days of an influenza hospitalization," Shay said. "We didn't see a significant effect on post-influenza deaths during the 2013-2014 H1N1 season."
The study was published in The Journal of Infectious Diseases.