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.