A study published in The Journal of Infectious Diseases indicated that high-dose influenza vaccine was significantly more effective for preventing post-influenza deaths among older adults than standard-dose vaccine.
“It has been recognized at least since the 1957 A (H2N2) pandemic that older persons and those with some chronic health conditions, including pulmonary and cardiac compromise, are at the greatest risk of severe influenza outcomes,” David K. Shay, MD MPH, of the influenza division of the CDC, Atlanta, and colleagues wrote.
“This is the population that everybody worries about,” Shay said in a press release accompanying the study. “Many of the most serious outcomes of flu infections occur in older people.”
The researchers reviewed data from Medicare beneficiaries aged 65 years and older who received either a standard-dose (n = 1,683,264) or high-dose influenza vaccine (n = 1,039,654) during the 2012-2013 season, as well as recipients vaccinated during the 2013-2014 season (standard, n = 1,877,327; high-dose, n = 1,508,176). The primary outcome was death within 30 days after an emergency department or inpatient visit for influenza.
Overall, Shay and colleagues reported that there were 0.028 post-influenza deaths per 10,000 person-weeks among those who had received high-dose vaccines, and 0.038 deaths per 10,000 person-weeks among standard-dose recipients. The researchers wrote that overall comparative effectiveness was 24% (95% CI, 0.6%-42%). High-dose vaccine recipients were 36.4% less likely to die than standard-dose recipients in the 2012-2013 flu season (95% CI, 9%-56%). This fell to 2.5% in the 2013-2014 season (95% CI, -47% to 35%).
Researchers noted that the H3N2 influenza virus, which is linked to greater mortality in senior citizens, was predominant in the 2012-2013 season. H1N1 viruses, which are more susceptible to the standard-dose vaccine, were more common in 2013-2014.
“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 in the press release. “We didn’t see a significant effect on post-influenza deaths during the 2013-2014 H1N1 season.”
In an accompanying editorial, Arnold S. Monto, MD, of the University of Michigan School of Public Health, pointed out that Shay and colleagues’ findings fell in line with those of previous studies.
“This indicates 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,” Monto wrote. “The high-dose and adjuvanted approaches are welcome additions to our ability to counter effects of influenza, and they should be further investigated and used. They should be viewed as not the end, but the beginning, of programs leading to vaccines of higher effectiveness, longer duration and broader protection.” – by Andy Polhamus
Disclosure: Shay reports no relevant financial disclosures. Please see the full study for a complete list of all other researchers’ relevant financial disclosures. Monto reports personal fees from Novartis, as well as grants and personal fees from Sanofi-Pasteur, all outside of the submitted work.