This Phase 3 study will evaluate the efficacy of a Typhoid conjugate vaccine (Vi-TCV) in Malawi, Africa among children age 9 months through 12 years.

Participants will be randomized in a 1:1 ration to receive the study vaccine or the control vaccine (meningococcal group A conjugate vaccine - MCV-A).

Results

September 2022 - The Lancet published results of a nested substudy of a randomized, controlled trial. TCV was safe, well tolerated, and immunogenic in Malawian children aged 9 months to 12 years. Furthermore, in children younger than 1 year of age, TCV showed strong immunogenicity and no interference or safety concerns when coadministered with measles-rubella vaccine.

The findings in Malawian children are consistent with results from four other clinical trials of Typbar TCV in Africa and Asia. 

On September 16, 2021 The New England Journal of Medicine published the results of this clinical trial.

The intention-to-treat analysis included 28,130 children, of whom 14,069 were assigned to receive Vi-TCV and 14,061 were assigned to receive the MenA vaccine. Blood culture–confirmed typhoid fever occurred in 12 children in the Vi-TCV group (46.9 cases per 100,000 person-years) and in 62 children in the MenA group (243.2 cases per 100,000 person-years). Overall, the efficacy of Vi-TCV was 80.7% (95% confidence interval [CI], 64.2 to 89.6) in the intention-to-treat analysis and 83.7% (95% CI, 68.1 to 91.6) in the per-protocol analysis. In total, 130 serious adverse events occurred in the first 6 months after vaccination (52 in the Vi-TCV group and 78 in the MenA group), including 6 deaths (all in the MenA group). No serious adverse events were considered by the investigators to be related to vaccination.

CONCLUSIONS: Among Malawian children 9 months to 12 years of age, administration of Vi-TCV resulted in a lower incidence of blood culture–confirmed typhoid fever than the MenA vaccine.