Birth order and influenza vaccination: a comparative study of behaviors and intentions between first-time and...

This study investigates the impact of birth order on influenza vaccination behaviors and intentions among parents of children under 6 years of age, and identifies factors contributing to vaccination disparities to inform targeted strategies for reducing health inequities.

A national cross-sectional survey was conducted in China (July - August 2024) using stratified sampling, with 3,569 parents of children aged 0-6 completing a questionnaire based on the Determinants of Vaccine Hesitancy Matrix developed by the World Health Organization (WHO-DVH Matrix). Logarithmic regression examined the relationship between age and vaccine hesitancy/vaccination rates. Random forest analysis identified key predictors, while one-way ANOVA examined influencing factors.

Among respondents, 66.9% were first-time parents and 33.1% second-time parents. Vaccination rates for first-born children were lower than those for second-born children before 40 months (64.9% vs. 71.7%, p = 0.022), while vaccine hesitancy was higher among first-time parents before 49 months (58.6% vs. 49.9%, p < 0.001). These differences diminished after age three. Key predictors of vaccination intention included 'Immunization as a social norm' and the 'Reliability of vaccine supply.'

First-time parents demonstrate lower vaccination rates and higher hesitancy to children, particularly before age three, influenced by social norms and vaccine confidence. These findings provide empirical evidence for birth order-based strategies to improve vaccine equity.