The high-dose vaccine was significantly more efficacious in preventing flu-related deaths during a bad flu season.
The high-dose flu vaccine was 36% more effective at preventing deaths in older adults compared with the standard dose vaccine during the 2012-2013 season when H3N2 viruses were dominant.
As individuals age, they have an increasing risk of serious complications from theflu. In recent years, the CDC estimates that between 71% and 85% of flu-related deaths occurred among individuals 65 years or older.
For astudypublished in theJournal of Infectious Diseases, CDC and FDA investigators used data from Medicare beneficiaries 65 years or older who received the high-dose or standard-dose flu vaccine during the 2012-2013 and 2013-2014 flu seasons from community-located pharmacies.
In each of the seasons, more than 1 million recipients of each vaccine type were studied.
The results of the study showed that individuals who received a high-dose vaccine during the 2012-2013 season were 36% less likely to die in the 30 days following hospitalization, or following an emergency department visit that included a flu diagnosis, compared with those who took the standard-dose vaccine.
H3N2 flu viruses are typically associated with higher mortality in older adults, as was the case during the 2012-2013 season.
In the 2013-2014 season, the H1N1 viruses dominated. The investigators found that the standard-dose vaccine had a higher efficacy than the prior season, whereas the high-dose vaccine was not significantly better in preventing deaths among the study patients.
“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,” said author David K. Shay, MD, MPH, of the CDC’s Influenza Division. “We didn’t see a significant effect on post-influenza deaths during the 2013-2014 H1N1 season.”
In a related editorial commentary, Arnold S. Monto, MD, who was not involved in the study, said the findings matched well with prior data that showed the high-dose flu vaccine is more effective against uncomplicated flu illness and hospitalization.
“This indicated that improvement in our 70-year-old influenza vaccines is possible, and to get there more quickly we should not ignore older technologies while working on more dramatic advances,” Dr Monto wrote.