High-Dose Influenza Vaccine in H3N2 Season More Effective in Seniors
Researchers compared high-dose vs standard-dose influenza vaccines in preventing deaths in seniors during 2012–2013 and 2013–2014.
During a severe flu season, a high-dose influenza vaccine appears to be significantly more effective than a standard-dose vaccine in preventing post-influenza deaths among older adults. These are the findings of a study published The Journal of Infectious Diseases.
The high-dose influenza vaccine was first approved in 2009 for adults 65 years of age and older as this population tends to run a higher risk of serious complications from flu. Compared to H1N1 or influenza B viruses, H3N2 viruses have been associated with increased mortality in this age group.
In order to compare the effectiveness of these flu vaccines on older patients, researchers from the Centers for Disease Control and Prevention (CDC), the Centers for Medicare & Medicaid Services, and the Food and Drug Administration (FDA) identified Medicare beneficiaries 65 years of age and older who received either the high-dose or standard-dose flu vaccines in community-located pharmacies. The primary outcome of the study was death in the 30 days after an inpatient or emergency department visit that included an influenza diagnosis.
High-dose vaccine was given to 1,039,645 patients during the 2012–2013 season and 1,508,176 during the 2013–2014 season. Standard-dose vaccine was given to 1,683,264 patients during the 2012–2013 season and 1,877,327 during the 2013–2014 season. During the 2012–2013 season, when H3N2 was predominant, patients who received the high-dose vaccine were 36.4% less likely to die 30 days following hospitalization or emergency department visit, compared to those who received the standard-dose vaccine. During the 2013–2014 season, when H1N1 was predominant, the high-dose vaccine was not significantly better at preventing deaths (2.5%) than the standard-dose vaccine which appeared to be more effective during this season than in the previous one.
"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 study author David K. Shay, MD, MPH, of CDC's Influenza Division, "We didn't see a significant effect on post-influenza deaths during the 2013-2014 H1N1 season."
Shay DK, Chillarige Y, Kelman J, et al. Comparative effectiveness of high-dose versus standard-dose influenza vaccines among US Medicare beneficiaries in preventing postinfluenza deaths during 2012–2013 and 2013–2014 [published online March 2, 2017]. J Infect Dis. doi: 10.1093/infdis/jiw641