Alternative Childhood Vaccination Schedules in Israel: A Mixed-Methods Study on Prevalence, Patterns, and Public Health Implications

<b>Background/Objectives</b>: Vaccination programs are highly effective public health interventions, yet parental hesitancy toward combination vaccines has led to growing demand for alternative vaccination schedules, defined in this study as parental requests to split or replace recommended combination vaccines with single-antigen vaccines for non-clinical reasons. While parental attitudes have been widely studied, little empirical evidence exists on the real-world use of single-antigen vaccines and their public health implications in countries with otherwise high coverage. This study examined the prevalence patterns and parental motivations for requesting such alternative vaccination schedules in Israel, where national guidelines recommend specific combination vaccines, including measles-mumps-rubella-varicella (MMRV) and the pentavalent diphtheria-tetanus-pertussis-inactivated polio-Haemophilus influenzae type b (DTaP+IPV+Hib) vaccines, but informal accommodations exist. <b>Methods</b>: A mixed-methods design was employed: a retrospective cohort analysis of vaccination data from 2018 to 2021 (before and during the COVID-19 pandemic) focused on measles (first dose at 12 months) and pertussis (four-dose primary series), followed by semi-structured interviews with Maternal and Child Health clinic providers, policymakers, and parents. <b>Results</b>: Alternative vaccination schedules involving single-antigen measles or pertussis vaccines are occasionally used despite official policy, accounting for less than 1% of vaccinations overall. Outcomes include delayed administration, lower uptake of combination vaccines, and incomplete protection in certain groups. Parents cited safety concerns, fear of immune overload, and mistrust of authorities. These concerns were often amplified by misinformation, while providers described balancing parental preferences with the need for adequate coverage. <b>Conclusions</b>: This study provides new evidence on how vaccine hesitancy translates into service utilization, highlights the tension between individualized parental decision-making and contribution to collective health, and underscores the need for communication, policy strategies and service designs that sustain high coverage while addressing community-specific concerns.