With influenza vaccine, bigger may be better
Compared with standard vaccination, a beefed-up flu shot better protects older adults against the virus, researchers report in the Aug. 14 New England Journal of Medicine.
The elderly are at higher risk of flu because immunity wanes with age, and aging decreases the body's ability to take full advantage of a vaccination. In 2009, a “high-dose” flu shot for people age 65 and older was approved. While the vaccine boosts the immune response, it had been unclear whether that translated into fewer cases of the flu.
To find out, researchers randomly assigned more than 30,000 elderly people in the United States and Canada to get the high-dose or standard flu shot during fall 2010 and fall 2011. Afterward, the scientists tabulated who got sick during the subsequent flu seasons. Lab tests confirmed that about 1.9 percent of people getting the standard vaccination and 1.4 percent of those getting the heftier shot developed the flu, the researchers report. That increase in protection from the high-dose vaccine suggests that one-fourth of “breakthrough” infections — those hitting people even though they had gotten a standard shot — could be prevented, the authors say.
The stronger shot contains more flu protein than the other one. Side effects from the shots were minor. The study was led by researchers at vaccine maker Sanofi Pasteur, which also funded it.
C.A. DiazGranados et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. New England Journal of Medicine. Vol. 371, August 14, 2014, p. 635. doi: 10.1056/NEJMoa1315727.
T.H. Saey. Flu antibodies can make disease worse. Science News. Vol. 184, October 5, 2013, p. 18.
A.R. Falsey et al. Randomized, double-blind controlled phase 3 trial comparing the immunogenicity of high-dose and standard-dose influenza vaccine in adults 65 years of age and older. Journal of Infectious Diseases. Vol. 200, July 15, 2009, p. 172. doi: 10.1086/599790.