End-of-Season Flu Vaccinations Decline When LAIV Is Unavailable

During the 2016-2017 influenza season when the live attenuated influenza vaccine (LAIV) was not recommended, end-of-season vaccination rates were lower among children who had received LAIV during the 2015-2016 season, according to a recent study.

For the 2016-2017 influenza season, the Centers for Disease Control and Prevention (CDC) recommended against using LAIV. However, the perceived effectiveness and ease of administration of LAIV are key determinants of parents’ and families’ decisions to vaccinate their children.
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For their study, the researchers assessed data from a single primary care pediatric center in Pennsylvania serving approximately 12,500 patients. For children ages 2 to 17 years, early season and end-of-season vaccination rates during the 2015-2016 and 2016-2017 seasons were recorded. Early season was defined as prior to November 1, and end-of-season was defined as prior to March 1.

Rates of repeat vaccinations, or the proportion of children who received the influenza vaccination in one season and were also vaccinated in the next season, were also recorded for the 2015-2016 and 2016-2017 influenza seasons. Predictors of repeat vaccinations were determined using a logistic regression model adjusting for race, ethnicity, age, insurance type and type of vaccination.

During the 2016-2017 season when LAIV was not offered, early vaccination rates were significantly higher (24.7% vs 22.8%) compared with the 2015-2016 season when LAIV was offered. However, compared with 2015-2016 rates, end-of-season vaccination rates were lower (50.4% vs 52.0%) during the 2016-2017 influenza season.

Following adjustment for covariates, results indicated that patients who had received the inactivated influenza vaccine (IIV) in the 2015-2016 season were more likely to receive a repeat vaccination during the 2016-2017 season vs those who had received LAIV during the 2015-2016 season.

“End-of-season vaccination rates were lower in [2016-2017] when LAIV was not recommended, particularly among children who received LAIV in the preceding year. Unavailability of LAIV in the [2016-2017] season may have impacted influenza vaccination convenience and perceived effectiveness, two factors which could influence vaccine uptake in pediatric populations.

—Christina Vogt

Reference:

Fogel B, Hicks S. Influenza vaccination rates in children decline when the live attenuated influenza vaccine is not recommended. Vaccine. 2017;35(39):5278-5282. https://doi.org/10.1016/j.vaccine.2017.07.067.