One-month evaluation of safety and immunogenicity of a Vi-DT typhoid conjugate vaccine (Bio-TCV®) in Indonesian subjects 6 months to 45 years: A phase III randomized clinical trial

Background: Typhoid fever typically affects children and young adults and is a considerable cause of morbidity and mortality. Vaccination is the most effective preventive strategy to control typhoid fever in the short to medium term. However, in most endemic countries do not have a typhoid vaccine that is suitable for children below 2 years old. Methods: This is a randomized, observer blinded phase III trial using Vi-DT typhoid conjugate vaccine and an already WHO licensed prequalified (PQed) typhoid conjugate vaccine (Typbar TCV) as control. About 936 healthy subjects were recruited and divided into 3 age groups: infants group aged 6–24 months, children group aged 2–11 years, adolescents and adults group aged 12–45 years, and followed up till 28 days post vaccination. Blood sample was taken at pre-vaccination and at 28th day post vaccination to evaluate immunogenicity. Results: The most common immediate local reaction was pain in all age groups, followed by redness. The most common immediate systemic reaction in the infant group was irritability while in the adults and children group was muscle pain. The intensity of reactions was mostly mild and moderate. Severe reactions were in the form of pain and fever. Reactions mostly resolved within 48 h. Seroconversion at 28 days in the Vi-DT group was higher in both adults and children compared to the PQed typhoid conjugate vaccine, Typbar-TCV (p = 1.000; p = 0.250), respectively. The Geometric Mean Titer (GMT) in the Vi-DT group was higher in adults (p = 0134), whereas the PQed typhoid conjugate vaccine Typbar-TCV demonstrated a higher GMT in children and infants (p = 0.277; p = 0.884), respectively. Conclusion: Vi-DT typhoid conjugate vaccine (Bio-TCV®) is safe and immunogenic in subjects 6 months to 45 years old. Clinical trial registration number. NCT04051268, registration date: 09/08/2019.