HealthDay News — It may be best for older adults to wait until October to receive their flu vaccine, unless that delay would cause them to skip getting their flu shot altogether, according to a study published in the April issue of the American Journal of Preventive Medicine.

Kenneth J. Smith, M.D., from the University of Pittsburgh School of Medicine, and colleagues developed a model to compare influenza likelihood in older adults with either status quo vaccination (August to May) to maximize vaccine uptake or vaccination compressed to October to May (to decrease waning vaccine effectiveness impact). The model relied on U.S. Centers for Disease Control and Prevention data on influenza incidence and vaccination parameters, as well as previous analyses that showed absolute vaccine effectiveness decreased by 6 to 11 percent per month.

The researchers found that compressed vaccination, if it did not decrease vaccine uptake, would avert ≥11,400 influenza cases in older adults during a typical season. However, if vaccine uptake was decreased as a result of compressed vaccination or if there was an early peak to the influenza season, there would more influenza cases. Compressed vaccination was never favored in probabilistic sensitivity analyses if it decreased absolute vaccine uptake by >5.5 percent in any scenario. Status quo vaccination was favored when influenza peaked early.

“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,” Smith 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.”

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