Immunogenicity and Safety of Typhoid Conjugate Vaccine in Healthy Indian Subjects: A Randomized, Active-controlled, Comparative Clinical Trial.

Objective: To compare the immunogenicity and safety of an investigational typhoid Vi conjugate vaccine (Test TCV) with a marketed typhoid Vi conjugate vaccine (Comparator TCV).

Design: Randomized, controlled trial.

Setting: Tertiary care and multispecialty hospitals.

Participants: 240 healthy subjects of 6 months to 45 years. Pediatric (<18 years) subjects were enrolled after day 21 safety assessment of adult subjects.

Intervention: Participants received a single-dose of test TCV or comparator TCV at baseline and were followed up for 6 weeks post-vaccination.

Main Outcome Measure: Primary variable was to demonstrate non-inferiority of the test TCV with the comparator TCV for seroconversion post-vaccination (³4-fold rise in antibody titre). Secondary variables were seroconversion in the adult and pediatric cohorts, and geometric mean titre of antibodies while the safety was based on reported adverse events.

Results: A total of 117 subjects (Adult-58, Pediatric-59) and 119 subjects (Adult-60, Pediatric-59) in test and comparator group, respectively completed the study. The seroconversion rate with test TCV (overall-94.8%, adult-96.6% and pediatric-93.1%) was non-inferior to comparator TCV (overall-91.6%, adult-91.7% and pediatric-91.5%). The geometric mean titres of antibodies (EU/mL) at baseline (test TCV: overall-7.6, adult-10.0, and pediatric-5.7; and comparator TCV: overall-8.0, adult-12.0, and pediatric-5.3) and at end of study (test TCV: overall-1121.0, adult-1411.0 and pediatric-891.1; and comparator TCV: overall-1104.0, adult-1199.0 and pediatric-1014.0) were also comparable between the groups (P>0.05 for all). The most common adverse event was injection-site pain followed by fever in both the groups.

Conclusions: The immunogenicity and safety of test TCV is comparable to already marketed comparator TCV.