Typhoid Conjugate Vaccine Introduction in Madagascar (TyMA): Evaluation of the Real-World Effectiveness of the Vi-CRM197 Typhoid Conjugate Vaccine in Madagascar (TyMA)
This study evaluates the real-world effectiveness, safety, and immunogenicity of a single dose of the Vi-CRM197 typhoid conjugate vaccine (TCV) delivered through a mass vaccination campaign in selected districts of Madagascar. The study targets individuals aged 9 months to 45 years living in defined catchment areas with a high burden of typhoid fever.
The project integrates three components: a population census with geographic mapping, a vaccination campaign using a WHO-prequalified Vi-CRM197 TCV, and prospective surveillance for typhoid fever. Vaccine effectiveness will be assessed by comparing the incidence of blood culture-confirmed Salmonella Typhi infection among vaccinated and unvaccinated individuals during follow-up. Additional outcomes include clinically suspected typhoid fever, severe disease, vaccine safety, immunogenicity, antibiotic use and consumption, and carriage of antimicrobial resistance (AMR) markers.
The study aims to generate real-world evidence to inform public health decision-making regarding typhoid vaccine introduction and its broader impact on disease burden and antimicrobial resistance in endemic settings.
Tutkimuksen yleiskatsaus
Tila
Interventio / Hoito
Yksityiskohtainen kuvaus
Typhoid fever, caused by Salmonella enterica serovar Typhi, remains a major public health problem in many low- and middle-income countries, particularly in settings with limited access to safe water and sanitation. The emergence of antimicrobial resistance further complicates treatment and underscores the importance of preventive strategies such as vaccination. Typhoid conjugate vaccines (TCVs) have demonstrated efficacy in clinical trials, but data on their real-world effectiveness and broader population impact in African settings remain limited.
The TyMA study evaluates the impact of a mass vaccination campaign using a WHO-prequalified Vi-CRM197 TCV in selected districts of Madagascar. The study employs a population-based design integrating a baseline census, vaccination activities, and longitudinal surveillance.
Eligible individuals aged 9 months to 45 years will receive a single intramuscular dose of Vi-CRM197 during a community vaccination campaign.
Vaccine effectiveness will be assessed through both active and enhanced facility-based surveillance for typhoid fever over approximately three years Blood culture testing will be performed for suspected cases to identify laboratory-confirmed S. Typhi infection. Effectiveness estimates will be derived by comparing incidence rates between vaccinated individuals and unvaccinated controls within the censused population.
Subgroups of participants will be enrolled in additional cohorts to evaluate specific outcomes:
- Safety cohort: Active monitoring for adverse events following vaccination
- Immunogenicity cohort: Measurement of anti-Vi IgG antibody responses over time
- Active follow-up subpopulation: Regular household visits to identify febrile illness and healthcare utilization
- AMR cohort: Assessment of antimicrobial use, consumption, and carriage of antimicrobial resistance markers
Passive surveillance in selected healthcare facilities will complement active follow-up to capture cases presenting for care. Data on antibiotic prescribing, hospitalization, and clinical outcomes will also be collected.
The study will assess direct, indirect, and overall vaccine protection at the population level and explore the impact of vaccination on antimicrobial use and resistance patterns. Findings are expected to provide critical evidence to support national and regional policy decisions regarding typhoid vaccine introduction and strategies to mitigate antimicrobial resistance.
Opintotyyppi
Ilmoittautuminen (Arvioitu)
Vaihe
- Vaihe 4
Yhteystiedot ja paikat
Opiskeluyhteys
- Nimi: Florian Marks
- Puhelinnumero: +82 10-8703-3813
- Sähköposti: fmarks@ivi.int
Opiskelupaikat
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Antananarivo, Madagaskar
- Rekrytointi
- MIVR
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Ottaa yhteyttä:
- Raphael Rakotozandrindrainy
- Puhelinnumero: +261 32 50 267 21
- Sähköposti: rakrapha13@gmail.com
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Osallistumiskriteerit
Kelpoisuusvaatimukset
Opintokelpoiset iät
Hyväksyy terveitä vapaaehtoisia
Sukupuolet, jotka voivat opiskella
Kuvaus
Inclusion Criteria:
- Age 9 months to 45 years at the time of vaccination
- Resident of the defined study catchment area in Madagascar
- Parent(s), legal guardian, or participant (if adult) able and willing to provide written informed consent (and assent where applicable)
- Willing to comply with study procedures and follow-up for the duration of the study
Exclusion Criteria:
- Any medical or social condition that, in the opinion of the investigator, would interfere with participation or study procedures
- Known allergy or hypersensitivity to any component of the Vi-CRM197 typhoid conjugate vaccine
- Parent(s), legal guardian, or participant unwilling or unable to provide informed consent/assent
Opintosuunnitelma
Miten tutkimus on suunniteltu?
Suunnittelun yksityiskohdat
- Ensisijainen käyttötarkoitus: Ennaltaehkäisy
- Jako: Ei käytössä
- Inventiomalli: Yksittäinen ryhmätehtävä
- Naamiointi: Ei mitään (avoin tarra)
Aseet ja interventiot
Osallistujaryhmä / Arm |
Interventio / Hoito |
|---|---|
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Kokeellinen: Vaccination Campaign: Vi-CRM197 Typhoid Conjugate Vaccine
Participants aged 9 months to 45 years residing in the defined catchment area will be offered a single intramuscular dose of the Vi-CRM197 typhoid conjugate vaccine as part of a population-based vaccination campaign. Vaccine effectiveness will be evaluated prospectively through active and facility-based surveillance for typhoid fever. |
Single-dose Vi-CRM197 typhoid conjugate vaccine administered intramuscularly to age-eligible individuals during a mass vaccination campaign. The vaccine is WHO-prequalified and intended to prevent infection with Salmonella enterica serovar Typhi. |
Mitä tutkimuksessa mitataan?
Ensisijaiset tulostoimenpiteet
Tulosmittaus |
Toimenpiteen kuvaus |
Aikaikkuna |
|---|---|---|
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Incidence of blood culture-confirmed typhoid fever (Salmonella Typhi)
Aikaikkuna: From census enrollment up to 52 months
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Incidence of typhoid fever defined as isolation of Salmonella enterica serovar Typhi from blood culture among individuals residing in the study catchment area. Vaccine effectiveness will be estimated by comparing incidence between individuals who received a single dose of Vi-CRM197 typhoid conjugate vaccine during the vaccination campaign and unvaccinated individuals within the censused population using active and enhanced facility-based surveillance. |
From census enrollment up to 52 months
|
Toissijaiset tulostoimenpiteet
Tulosmittaus |
Toimenpiteen kuvaus |
Aikaikkuna |
|---|---|---|
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Incidence of clinically suspected typhoid fever
Aikaikkuna: From census enrollment up to 52 months
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Incidence of clinically suspected typhoid fever among residents of the study catchment area identified through active household surveillance and enhanced facility-based surveillance, regardless of laboratory confirmation. Comparisons will be made between vaccinated and unvaccinated individuals. |
From census enrollment up to 52 months
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Incidence of severe typhoid fever
Aikaikkuna: From census enrollment up to 52 months
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Incidence of severe typhoid fever, including cases requiring hospitalization or presenting with severe complications, among vaccinated and unvaccinated individuals in the study population |
From census enrollment up to 52 months
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Solicited and unsolicited adverse events following vaccination
Aikaikkuna: Solicited adverse events: Days 0-7 post-vaccination of a subset of participants; Unsolicited adverse evetns : up to 28 days pos vaccination. Aerious adverse events: From vaccination enrollment up to 52 months
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Occurrence of solicited local and systemic adverse events within 7 days after vaccination and unsolicited adverse events and serious adverse events during follow-up among participants receiving the Vi-CRM197 vaccine. |
Solicited adverse events: Days 0-7 post-vaccination of a subset of participants; Unsolicited adverse evetns : up to 28 days pos vaccination. Aerious adverse events: From vaccination enrollment up to 52 months
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Anti-Vi IgG antibody response following vaccination
Aikaikkuna: Baseline to 24 months post-vaccination
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Immunogenicity assessed by seroconversion (≥4-fold rise in anti-Vi IgG titers from baseline) and geometric mean titers measured in a subset of vaccinated participants at predefined time points after vaccination. |
Baseline to 24 months post-vaccination
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Carriage of antimicrobial resistance markers
Aikaikkuna: Baseline to 12 months
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Prevalence and changes in antimicrobial resistance markers in gastrointestinal and respiratory samples among vaccinated and unvaccinated individuals in a subset cohort. |
Baseline to 12 months
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Yhteistyökumppanit ja tutkijat
Sponsori
Opintojen ennätyspäivät
Opi tärkeimmät päivämäärät
Opiskelun aloitus (Todellinen)
Ensisijainen valmistuminen (Arvioitu)
Opintojen valmistuminen (Arvioitu)
Opintoihin ilmoittautumispäivät
Ensimmäinen lähetetty
Ensimmäinen toimitettu, joka täytti QC-kriteerit
Ensimmäinen Lähetetty (Todellinen)
Tutkimustietojen päivitykset
Viimeisin päivitys julkaistu (Todellinen)
Viimeisin lähetetty päivitys, joka täytti QC-kriteerit
Viimeksi vahvistettu
Lisää tietoa
Tähän tutkimukseen liittyvät termit
Avainsanat
Muita asiaankuuluvia MeSH-ehtoja
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