Typhoid
Conditions
Keywords
typhoid vaccine, Salmonella Typhi, typhoid fever
Brief summary
This study evaluated the persistence of immunity following primary typhoid conjugate vaccination in early childhood and assessed the immunogenicity and safety of a booster dose administered 5-6 years later. Children previously enrolled in a Phase 2 randomized clinical trial of Vi-tetanus toxoid conjugate vaccine (Vi-TT) were re-enrolled at 6-7 years of age. Participants who previously received Vi-TT received a booster dose of Vi-CRM, while control participants received their first TCV dose. Anti-Vi IgG antibody responses were measured at baseline and 28 days post-vaccination. Safety was assessed through solicited and unsolicited adverse events. This study provides data on durability of TCV immunity and the potential role of booster dosing in endemic settings.
Detailed description
This prospective, open-label interventional study followed children previously enrolled in a Phase 2 randomized controlled trial of Vi-TT administered in infancy. Approximately 5-6 years later, participants were re-contacted and assigned to receive either a booster TCV dose (Vi-CRM) or a first TCV dose depending on prior vaccination status. Immunogenicity was assessed using anti-Vi IgG ELISA assays at baseline and 28 days post-vaccination. Safety outcomes included solicited and unsolicited adverse events and serious adverse events. The study was conducted at a single clinical site in Ouagadougou, Burkina Faso.
Interventions
BIOLOGICALVi capsular polysaccharide-CRM197 conjugate vaccine (Vi-CRM), 0.5 mL IM
Typhoid conjugate vaccine: Vi capsular polysaccharide conjugated to CRM197 carrier protein, administered as 0.5mL intramuscularly
Sponsors
Kathleen Neuzil
Groupe de Recherche Action en Sante
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
PREVENTION
Masking
NONE
Intervention model description
Participants vaccinated previously at age 9-23 months with either typhoid conjugate vaccine (Vi-TT typhoid conjugate vaccine) or control vaccine (inactivated polio vaccine) as part of a clinical trial receive a dose of typhoid conjugate vaccine (Vi-CRM typhoid conjugate vaccine) as a first or second typhoid conjugate vaccine dose, respectively.
Eligibility
Sex/Gender
ALL
Age
6 Years to 7 Years
Healthy volunteers
Yes
Inclusion criteria
* Male or female children previously enrolled in the 2018-2019 Phase 2 typhoid conjugate vaccine trial * Residence within study area * Parent/guardian provides informed consent
Exclusion criteria
* Receipt of blood products within 6 months * Prior typhoid conjugate vaccine receipt outside the study * Medical condition interfering with evaluation * Acute illness or fever prior to vaccination (temporary exclusion)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Anti-Vi IgG Antibody Response (Immunogenicity) | Baseline (Day 0) and Day 28 post-vaccination | Geometric Mean Titers (GMT) and fold-rise in anti-Vi IgG |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Seroconversion rate | Day 28 | Proportion of participants achieving ≥4-fold increase in anti-Vi IgG |
| Solicited adverse events | Days 0-7 | Local and systemic adverse events within 7 days post-vaccination |
| Unsolicited adverse events | Days 0-28 | Any non-solicited adverse events |
| Serious adverse events | Days 0-28 | Any serious adverse events |
Countries
Burkina Faso
Outcome results
None listed