A phase II clinical trial of a Vi-DT typhoid conjugate vaccine in healthy Indonesian adolescents and adults: one-month evaluation of safety and immunogenicity

Background: Typhoid fever is commonly found until today, especially in developing countries. It has fatal complications and measures must be taken to reduce the incidence of typhoid. Vaccinations are a key factor in prevention. This is a phase II randomized observer-blind clinical trial on a novel Vi-DT conjugate vaccine on 200 subjects 12 to 40 years of age. Methods: Subjects were screened for eligibility after which a blood sample was taken and one dose of vaccine was administered. Investigational vaccine used was Vi-DT and control was Vi-PS. Twenty-eight days after vaccination, subjects visited for providing blood sample to assess immunogenicity and were asked about local and systemic adverse reactions that occurred in the first 28 days. Results: Subjects had minor adverse reactions. Pain was the most common local reaction. Muscle pain was the most common systemic reaction. There were no serious adverse events up to 28 days post vaccination. Seroconversion rates were 100% in the Vi-DT group and 95.96% in the Vi-PS group. Post vaccination GMTs were increased in both groups but it was significantly higher in the Vi-DT group (p < 0.001). Conclusions: Vi-DT typhoid conjugate vaccine is safe and immunogenic in healthy Indonesian subjects 12 to 40 years. Trial registration: Approved by ClinicalTrials.gov. Clinical trial registration number: NCT03460405. Registered on 09/03/2018. URL: https://clinicaltrials.gov/ct2/show/NCT03460405 .