Association between influenza vaccination and antibiotic prescription in pediatric population

INTRODUCTION: A major cause of antimicrobial resistance (AMR) is inappropriate antibiotic consumption in humans. The scientific literature is discordant on the impact of the indirect effect that influenza vaccination in the pediatric population in counteracting AMR. This study aims to evaluate the impact of influenza vaccination on antibiotic prescriptions in the pediatric population in Tuscany (Italy) for the 2019-20 influenza season. METHODS: A retrospective cohort study was performed from current data obtained from the Tuscany Regional Health Authority. We recruited all the children between 6 months-6 years old who underwent influenza vaccination between September 2019 and April 2020. Each vaccinated child was matched with an unvaccinated by Propensity Score Matching for sex, age, area of residence, exemptions, previous hospitalization, and deprivation index. The consumption of beta-lactam antibiotics and macrolides (main drugs used for pediatric respiratory infections) between 15 days after vaccination and the end of the study period was measured for each child. The outcome is the number of antibiotic prescriptions per 100 weeks at risk. The association between influenza vaccination and antibiotic consumption was measured by estimating relative risk from a Poisson regression model. RESULTS: The study population consisted of 23,034 vaccinated children. Antibiotic prescriptions were 2.27 per 100 weeks at risk in the unvaccinated and 3.01 per 100 weeks in the vaccinated. Antibiotic prescribing in vaccinated children was higher than in the unvaccinated, with a relative risk of 1.33 [CI 95% 1.29-1.35; p < 0.00001]. CONCLUSIONS: The results show a higher prescription of beta-lactams and macrolides in children vaccinated with influenza vaccine than in unvaccinated children during the study period. This result may depend on factors that cannot be measured with the available data, such as the number of visits to the pediatrician and the medical's propensity to prescribe antibiotics. KEY MESSAGES: • The results of this study showed that vaccinated children had a higher rate of antibiotic prescriptions than unvaccinated children. • Factors not measured, such as the frequency of pediatrician visits and medical prescribing habits, may have influenced the higher rate of antibiotic prescriptions in vaccinated children.