One-month follow up of a randomized clinical trial-phase II study in 6 to <24 months old Indonesian subjects: Safety and immunogenicity of Vi-DT Typhoid Conjugate Vaccine.

Introduction: World Health Organization estimates the annual global incidence of typhoid fever at 11-21 million cases and approximately 128 000 to 161 000 deaths. The currently used Vi-polysaccharides (Vi-PS) vaccines have been proven to be safe and efficacious in children 2 years and above. However, poor immunogenicity of Vi-PS was observed in children below 2 years of age. This Phase II study is the continuation of the previously published Phase I study that aims to evaluate the safety and immunogenicity of a novel Vi-DT Typhoid Conjugate Vaccine (Bio Farma) in subjects 6 to <24 months.

Methods: An interventional, blinded, comparative, randomized phase II study was conducted from July 2018 until January 2019. There were 200 healthy subjects divided into two groups: trial and control groups. Inactivated poliovirus vaccine was given to control group. Immediate and delayed local and systemic reactions up to 28 days post vaccination were recorded. Antibody titers were measured prior to vaccination (V1) and 28 days post vaccination (V2).

Result: The study showed that the seroconversion of Vi-DT vaccine 98.99%. One dose of Vi-DT vaccine induced higher geometric mean titers (GMT) in all subjects compared to that of baseline. Pain was the most common immediate and delayed local reaction. Immediate and delayed systemic reactions that mostly occurred was fever. There were no serious adverse events reported within 28 days post vaccination.

Conclusion: The novel typhoid Vi-DT conjugate vaccine is safe and immunogenic in children 6 to <24 months.

Trial Registration Number: NCT03460405.