Climate change reshapes patterns of vaccine-preventable diseases by altering the environmental and social contexts that drive transmission. Rising temperatures, changing rainfall, and more frequent extreme weather influence vector range, seasonality, and the resilience of health systems, producing shifts in where and when diseases like dengue, yellow fever, and measles are likely to appear. Evidence from climate and health research underscores these mechanisms and their implications for vaccination strategies. Kristie Ebi, University of Washington, has documented links between warming climates and expanded seasonal windows for vector-borne infections, while Paul R. Epstein, Harvard Medical School, has described how ecosystem changes modify pathogen exposure and human vulnerability.
Environmental drivers
Warming and altered precipitation change mosquito and tick habitats, permitting vectors to colonize higher latitudes and elevations that previously were too cold. This expands the geographic risk for diseases such as dengue and Japanese encephalitis and can lengthen transmission seasons, increasing the number of infectious cycles per year. Changes in humidity and extreme rainfall events also affect breeding sites and pathogen survival. These environmental shifts interact with local ecology and livelihoods; for example, mountain communities and temperate-zone populations with low prior exposure may face new and unexpected outbreaks, complicating vaccine prioritization and coverage.
Health system and social impacts
Extreme weather, flooding, and heatwaves disrupt routine immunization by damaging clinics, interrupting supply chains, and breaking the vaccine cold chain. Displacement of populations after storms or drought increases crowding and reduces access to health services, raising the risk of outbreaks of highly transmissible vaccine-preventable diseases such as measles and poliovirus. Maria Neira, World Health Organization, has emphasized that health services resilience is critical for maintaining vaccination during climate-related emergencies. Social and cultural factors also matter: migration routes, trust in health authorities, and local beliefs shape vaccine uptake, so territorial and community contexts determine real-world risk patterns.
Together, these pathways mean that climate change does not create new vaccine-preventable pathogens but redistributes risk, stresses delivery systems, and alters timing and intensity of outbreaks. Strengthening surveillance, adapting immunization schedules to shifting seasonality, investing in cold-chain resilience, and tailoring outreach to affected communities are essential responses informed by interdisciplinary evidence from climate science and public health. Addressing these challenges requires integrating environmental monitoring with vaccination planning at local and national levels.