A compressed vaccine schedule for older adults could help increase uptake and decrease the impact of the influenza vaccine’s waning effectiveness as months go by, but such a schedule would not be beneficial if flu season peaks early or if a compressed schedule results in a decrease in vaccine uptake.
There is a debate in the healthcare community about when people should get their flu shot: as soon as the vaccine is available in August or later in the fall? A new analysis has found that when to get the vaccine depends on when the peak of flu season occurs.
The authors compared a compressed vaccination schedule (October to May) in older adults (65 years or older) with the status quo vaccination schedule (August to May). The study was published in American Journal of Preventive Medicine.
The status quo schedule is used to maximize vaccine uptake, but the risk is that the vaccine’s effectiveness wanes as time goes by. The compressed schedule decreases that waning effectiveness impact, but it could decrease overall vaccine uptake.
The authors examined average monthly incidence of influenza, as well as earlier and later peaks. They used data from the 2013-2014 and 2014-2015 flu seasons to forecast the number of cases, hospitalizations, and deaths for both scenarios (compressed vs status quo) with flu season peaking in December (early), February (normal), or April (late).
According to the results, a compressed schedule would prevent 11,400 or more influenza cases in older adults in a typical flu season, but only as long as the compressed vaccination schedule did not decrease vaccine uptake.
“There’s controversy in the public health community over whether influenza vaccination should happen as soon as the vaccine becomes available in August, or if it’s better to wait until later in the fall,” lead author Kenneth J. Smith, MD, MS, professor of medicine and clinical and translational science in the University of Pittsburgh’s Division of General Internal Medicine, said in a statement. “What we’ve found is that it’s a balancing act, but if a clinician believes a patient will return for vaccination in the fall, then our analysis shows that it is best if they advise that patient to wait.”
Some factors that would cause more influenza cases would be if vaccine uptake was affected by a compressed schedule or if the flu season has an early peak. The model projected that hundreds of adults could die if the flu season peaks early and they aren’t vaccinated in time.
The status quo was favored if a compressed schedule caused more than 5.5% of adults to not get the vaccination because they deferred it or if the season peaked early.
The findings should help physicians determine when their patients should get the vaccination, according to Smith. Those with multiple appointments a year can likely wait, but those who only come in for an annual check-up should get the shot in August.
“In all scenarios, simply getting vaccinated is the best way to avoid the flu,” said Smith. “If the choice is between getting the influenza immunization early or not getting it at all, getting it early is definitely better.”
Smith KJ, France G, Nowalk MP, et al. Compressed influenza vaccination in U.S. older adults: a decision analysis [published online February 14, 2019]. Am J Prev Med. doi: 10.1016/j.amepre.2018.11.015.