Efficacy, immunogenicity, and safety of typhoid conjugate vaccines in children and adolescents: a systematic review and meta-analysis.

BACKGROUND

Typhoid is a serious infectious disease that is highly prevalent in low and middle income countries (LMICs) and causes severe morbidity and mortality. Typhoid conjugate vaccines (TCVs) have been developed to prevent and control typhoid infection, however, overall and pooled evidence on vaccine efficacy, immunogenicity and safety profiles in the pediatric population is limited.

METHODOLOGY: We conducted a systematic review and meta-analysis on August 12, 2025 using randomized controlled trials (RCTs) that assessed the vaccine efficacy of TCVs in the pediatric population. Included studies compared TCVs with a well-defined control groups i.e. either placebo, MenA or SA 14-14-2 JE vaccine. The vaccine efficacy data were pooled and estimates were generated via random effects model. Data on immunogenicity and safety were also extracted.

RESULTS

A total of five RCTs, involving over 120,000 participants from Asia and Africa were included. Pooled vaccine efficacy of TCVs was 83% (95% CI 78-87%) with low heterogeneity (I2 = 28%). Age-stratified analysis revealed consistent results across age groups, though estimates in children < 2 years were not statistically significant. Immunogenicity outcomes demonstrated marked rises in Vi-IgG titres within 28 days of vaccination which progressively waned. The safety outcomes were favourable, with most adverse events being mild and self-limiting.

CONCLUSION

We conclude that TCVs are highly efficacious, immunogenic and safe among children, supporting their implementation in national immunization schedules. Further studies are needed to determine the duration of protection and the need for booster doses.