Hershey, PA—A recommendation by the CDC to avoid vaccine nasal spray this past flu season had some consequences, according to a new study.
An article in the journal Vaccine suggests that influenza vaccination rates in children might have dropped for the 2016-2017 influenza season because the nasal spray was not an option.
The study, conducted by Penn State College of Medicine researchers, points out that many parents, who perceived the nasal spray vaccine as less painful and more convenient, appeared to have a preference for it. They also might have been influenced by earlier studies that found live attenuated influenza vaccine (LAIV) to be more effective in young children than the injectable version.
The vaccine was found to be less effective than the shot in preventing the H1N1 flu, however, and the CDC recommended against the nasal spray for the 2016-2017 influenza season.
“We wanted to understand what happened to vaccination rates with this new recommendation,” explained study coauthor Ben Fogel, MD, MPH, Assistant Professor of Pediatrics at Penn State College of Medicine and medical director of Penn State Pediatric Primary Care. “Would this recommendation against nasal spray vaccine shake people’s confidence in the influenza vaccine in general or make them less likely to get it because they have to get a shot?”
To determine that, the researchers retrospectively assessed total vaccination rates in 9,591 Penn State Pediatrics patients aged 2 to 17 years, comparing the 2014-2015, 2015-2016, and 2016-2017 influenza seasons.
Without the option of the nasal spray, total influenza vaccination rates in pediatric patients were 1.6% lower in 2016-2017 than in 2015-2016 and dropped even further in children who had received the nasal spray the year before.
After adjustment for covariates, those who had received flu shots in the 2015-2016 season had higher odds (OR 1.32) of getting a repeat vaccination in the 2016–2017 season, compared with those who had received LAIV in the 2015–2016 season.
Still, the decline wasn’t as much as the researchers had feared.
“We worried that there was going to be a huge drop off in vaccination rates without the nasal spray available,” Fogel said. “We saw a drop off but I would not call it huge, which is reassuring.”
Nationally, the study points out, a 1.6% reduction in influenza vaccination rates would represent 1.2 million additional unvaccinated children.
“This could potentially lead to 4,385 additional influenza-related outpatient visits and 30 additional influenza-related hospitalizations among the 74 million children under the age of 18 in the U.S.,” the study authors emphasize.
Influenza vaccination rates early in the 2016-2017 season were higher by nearly 2% than they were early in the 2015-2016 season, but then dropped. Researchers say they have no explanation for that anomaly.
For children vaccinated in the 2015-2016 season, those who were black, Hispanic, aged 13 to 17 years, and had public insurance were less likely to get vaccinated again in 2016-2017.
“One thing we found that we didn’t expect to see was a large percentage of people who switched their vaccine preference from one year to the next, meaning that one year they didn’t get the influenza vaccine and the next year they did or vice versa,” Fogel said. “Our data showed that 35 to 50 percent of people change their minds about getting the influenza vaccine from one year to the next.”
While previous research suggested that past vaccination was a predictor of future immunization, this study suggests otherwise.
“Instead, it seems that people may not be either vehemently pro flu vaccine or anti flu vaccine; rather if it’s convenient, they’ll get the vaccine, and if it’s not convenient, they won’t go out of their way to get it,” Fogel noted.
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