Typhoid Conjugate Vaccine Trial Among Children Younger Than 2 Years in Ouagadougou, Burkina Faso

Overview

Typhoid fever is an illness that may cause mild effects in children, such as fever and feeling tired, or it may cause serious effects-- even death. A new typhoid vaccine has recently been recommended by the World Health Organization (WHO) to prevent typhoid in children. But this new typhoid vaccine has not been tested with all of the vaccines given to children in Burkina Faso. The investigators want to look at this new vaccine, and study how safe it is in children in Burkina Faso and how their immune systems respond to the vaccine when given with other vaccines, such as yellow fever and meningitis A vaccines. The investigators plan to vaccinate 100 children between the ages of 9-11 months, and 150 children between the ages of 15 months and 2 years, in Ouagadougou, Burkina Faso, with either the typhoid vaccine or a vaccine against another illness called polio. Children will have follow-up visits on days 3, 7, 28 and 180. One teaspoon of blood will be collected on days 0 and 28.

This study will be divided into two cohorts, by age, with separate study designs. The first cohort will include children 9 through 11 months of age. The second cohort will comprise children 15 through 23 months of age. The purpose of this detailed evaluation of safety and immunogenicity is to assess the reactogenicity of the vaccine and the immune responses to Vi-TCV. Serum specimens will be collected from all participants on study day 0 (before vaccination) and on post-vaccination study day 28 to quantify anti-Vi and anti-tetanus toxoid antibodies. All children will have an additional 0.5 mL of blood collected on study day 0 before study vaccination to test for the presence of malaria parasitemia at baseline. Children 9 through 11 months of age in the Ouagadougou study area will be eligible for the first age cohort, which will be a double-blind, individually randomized, controlled trial. Up to 100 children in this cohort will be randomized in a 1:1 ratio to receive Vi-TCV (Group 1) or IPV (Group 2). Participants will be unaware of which study vaccine, Vi-TCV or IPV, is received. Vi-TCV or IPV will be administered with measles-rubella vaccine (MR) and YFV, as per Burkina Faso Expanded Programme on Immunization (EPI) schedule. These 9 through 11-month-old children will have immunogenicity to Vi-TCV, YFV, and tetanus toxoid assessed on study days 0 and 28. Children 15 through 23 months of age in the Ouagadougou study area will be eligible for the second cohort, a randomized study of the safety and immunogenicity of Vi-TCV when co-administered with routine Expanded Programme on Immunisation (EPI) vaccines (MAV and MR) or given alone, and MAV immunogenicity when co-adminstered or given alone. Participants in this cohort (up to 150) will be randomized 1:1:1 to one of three treatment groups, as follows. The first group of participants (Group A) will receive Vi-TCV and IPV at study day 0, with a subsequent dose of MAV at study day 28; the second group of participants (Group B) will receive MAV and Vi-TCV at study day 0; the third group (Group C) will receive MAV and IPV at study day 0. All children will receive MR at study day 0. Cohort 1 will be unblinded on day 28 for safety and follow-up and to ensure MAV receipt in Group A. These 15 through 23-month-old children will have antibody to meningococcal A vaccine, anti-Vi antibody, and tetanus toxoid antibody assessed on study days 0 and 28. Participants in both cohorts will have home or clinic visits on days 3 and 7 following vaccination for solicitation of local and systemic adverse events. Non-serious adverse events will be assessed up until the study day 28 visit. Serious adverse events will be captured throughout study follow-up and actively during the study day 180 visit.