Abstract

Vaccine hesitancy, the delay in acceptance or refusal of vaccines despite availability, has
been identified by the World Health Organization as one of the top ten global health
threats. This comprehensive review synthesizes evidence from 140 studies (2000- 2025)
examining the causal relationship between vaccine hesitancy and the resurgence of
vaccine preventable bacterial diseases, including pertussis (whooping cough), invasive
pneumococcal disease, Haemophilus influenzae type b (Hib), meningococcal disease, diphtheria, and tetanus. We analyze the epidemiology of resurgence in high income
countries with high vaccine coverage but increasing exemption rates, the role of social
media and organized anti- vaccine movements, the impact of the COVID- 19 pandemic
on routine childhood immunization, and the documented outbreaks directly attributed to
vaccine refusal. Pertussis resurgence in the US, UK, Australia, and Europe provides the
strongest evidence: states and countries with declining pertussis vaccine coverage
experienced outbreaks 3- 10 times larger than those with stable coverage. Incomplete
vaccination schedules, alternative schedules, and clustering of unvaccinated individuals
drive outbreaks. Vaccine hesitancy disproportionately affects bacterial diseases with
high population transmission (pertussis, pneumococcus, Hib) and those requiring booster
doses. We recommend mandatory school vaccination policies without non-medical
exemptions, healthcare provider communication training, rapid outbreak response
protocols, and targeted community engagement to rebuild trust.