March 26, 2019
2 min read

Waiting to vaccinate older adults may reduce flu cases, deaths

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Kenneth J. Smith, MD, MS, FACP
Kenneth J. Smith

Vaccinating older adults against influenza from October to May instead of August to May could prevent at least 11,400 more influenza cases and hundreds of deaths when the influenza season peaks after mid-Winter, according to findings published in the American Journal of Preventive Medicine. But that positive effect would not hold during early-peak seasons, or if the compressed schedule meant fewer adults were vaccinated, researchers found.

“Delaying influenza vaccination until October can minimize waning protection that occurs as a flu season progresses, but only if there are no signs of an early influenza season peak and patients will return for vaccination in the fall,” Kenneth J. Smith, MD, MS, FACP, professor of medicine and clinical and translational science at the University of Pittsburgh Medical Center, told Infectious Disease News.

As the study noted, the effectiveness and protection of the influenza vaccine can decrease over time, especially among adults aged 65 years or older. Researchers have studied various ways to promote vaccination and increase uptake in this population. Studies have found that vaccination halves the risk for influenza-related hospitalizations in adults, that repeated vaccination over influenza seasons lowers the risk for severe influenza in older adults and that a high-dose vaccine is more effective than standard vaccines in this population.

“If there are any doubts whether a patient will return, vaccinate them when you can, whenever that is,” Smith said.

In their study, Smith and colleagues compared influenza likelihood in older adults who were vaccinated between August and May with adults who were vaccinated on a compressed schedule, between October and May. They collected and analyzed influenza incidence and vaccination parameters data from the CDC for the 2013-2014 and 2014-2015 influenza seasons in the United States, according to the study.

During a typical season, the researchers found that compressed vaccination would avert 11,400 influenza cases or more among older adults — as long as the approach did not decrease vaccine uptake. If uptake decreased, or if the influenza season peaked early, influenza cases would increase.

“Our analysis suggests that a compressed influenza vaccination season, which starts in October, could have public health benefits in older adults during most flu seasons if changing from the current policy — vaccinating as soon as vaccine is available — does not significantly affect overall vaccination rates,” Smith said. “However, compressed vaccination during an early peaking flu season, which [is] seen about a quarter of the time, could lead to more influenza cases and deaths.” – by Marley Ghizzone

Disclosure: Smith reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.