Safety, immunogenicity and non-interference of concomitant Typhoid Vi capsular polysaccharide-tetanus toxoid conjugate vaccine (Typbar-TCV (R)) and measles or measles-mumps-rubella vaccines in 8-9 months-old Indian children

We evaluated safety, reactogenicity, and immunogenicity when the WHO-prequalified single-dose Typhoid Vi-polysaccharide conjugate vaccine, Typbar-TCV (R), was administered concomitantly with measles (MV) or measles-mumps-rubella (MMR) vaccines in 8- or 9-month-old children. We enrolled 493 children who were randomized 2:1:1:1 to four groups to receive either TCV (0.5 mL intramuscularly) and MV (0.5 ml subcutaneously) concomitantly at 9 months of age (Group 1) with two subgroups given TCV booster 28 days (Group 1A) or 180 days (Group 1B) later, or MV on Day 0 and TCV on Day 28 (Group 2); or TCV at 8 months of age and MV 28 days later (Group 3), or MV only at 9 months of age (Group 4). All children received MMR at 15 months of age. We observed no statistically significant differences between group rates of solicited or unsolicited adverse events assessed throughout the study. Seroconversion rates for measles, mumps, and rubella antibodies were unaffected by concomitant administration with TCV, being similar in Groups 1, 2, and 3 and comparable to Group 4 (Control). IgG anti-Vi antibody titers were similar in all groups after primary Typbar-TCV (R) vaccination and were not increased by a second dose 28 days later. A small response to a booster dose of Typbar-TCV (R) given at 180 days did not achieve the high titers observed after the first dose, suggesting that booster vaccination may be more effective after a longer interval than 6 months. Typbar-TCV (R) can be safely co-administered with measles and MMR vaccines in children aged >= 9 months.