A narrative review published in Vaccines examines the use of Japanese encephalitis vaccines (JEVs) in low- and middle-income countries (LMICs), synthesizing evidence on their efficacy, safety, cost-effectiveness, and policy challenges. The authors find that existing JEVs — including live attenuated, inactivated, and chimeric formulations — consistently achieve high seroprotection rates (typically above 80 %) across diverse LMIC settings, with only mild and self-limiting adverse events reported. The live attenuated SA 14-14-2 vaccine (LAJEV) emerges as a particularly cost-effective option, with multiple economic evaluations indicating that immunization programs can avert significant morbidity and mortality while remaining well below conventional willingness-to-pay thresholds.
Despite the strong performance of JEVs, the review underscores that the key barriers to wider adoption in LMICs lie less in vaccine biology than in systems and policy constraints. Limited infrastructure, uncertain regulatory capacity, financing gaps, and a dearth of long-term follow-up data constrain program sustainability and scale. The authors call for tailored policy frameworks, increased domestic resource allocation, and stratified implementation strategies that respect local epidemiology and economic constraints. Strengthening pharmacovigilance, supporting mixed vaccine schedules, and integrating JE immunization into routine infant and adult health services are among the recommended priorities if LMICs are to close the immunity gap against this serious disease.
How can the findings be used?
The findings of this review inform ministries of health and immunization program managers in shaping evidence-based JE vaccination strategies tailored to local needs. Global partners such as GAVI and WHO can leverage these insights to strengthen implementation support and financing decisions. Policymakers and researchers can use the evidence to optimize resource allocation, close critical knowledge gaps, and embed JE prevention within broader public health strategies.
Thumbnail image credit: Gavi/2015/Bart Verweij
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