Clinical trial NCT05829772: Impact Study of Cholera Vaccination in Endemic Areas - Seroprevalence
Official title: Community-based Monitoring of Cholera Antibodies' Seroprevalence, and Home Follow-up of Positive Cases, in the Context of Cholera Vaccination Campaign, Democratic Republic of the Congo
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Cholera
Keywords: Cholera incidence rates
Mass vaccination campaign
V.Cholerae
Serial seroprevalence
Lead sponsor: Epicentre
Sponsor class: OTHER
Collaborators: name: Wellcome Trust
name: Institut Pasteur
name: Institut National de Recherche Biomédicale. Goma, République Démocratique du Congo
name: Ministry of Public Health, Democratic Republic of the Congo
name: Medecins Sans Frontieres, France
First posted: 2023-04-26
Enrollment: 7000
Sex: ALL
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: OTHER
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Participants are selected randomly in the community. GPS point selection is made on mapping of roofs from the area, and some roofs are randomly selected with appropriate GIS software. Persons living under the randomly selected roof are proposed to participate in the surveys, or close neighboors in case of refusal.

Brief summary: This project aims to fill this essential knowledge gap by assessing the impact of oral cholera vaccine mass campaigns in 2 sites (urban and rural) in DRC, described in this protocol. The evidence generated from this project will be key to develop future strategies regarding cholera vaccine use in endemic settings, including places with higher burden in terms of cholera mortality

Detailed description: The project will comprise three different components:

Clinical cholera surveillance to measure cholera diseases incidence in selected African hotspots targeted by vaccination.

Serial serological surveys to measure the prevalence of recent cholera infection (within the last 12 months).

Identification and follow up of individuals with positive V. cholerae shedding (symptomatic or asymptomatic) among sero-survey participants and among household members of cholera confirmed cases.

The present protocol relates to the setup of seroprevalence surveys and the follow up of individuals with positive V. cholerae shedding identified through seroprevalence surveys, in DRC.

This protocol will allow us to assess if a large vaccination campaign reaching high coverage in cholera hotspot in Africa can allow sustained control of cholera for at least two years, by fulfilling the following specific objectives:

1. To calculate the proportion of individuals infected with cholera recently (i.e. previous year or last 2 months) before the campaign distribution or in non-vaccinated zones (baseline survey, rural site) or following the mass OCV campaign and before the start of the usual cholera season (pre-season survey, urban site).
2. To assess proportion of individuals recently infected (i.e. infected in the last two months or in the last year) during the expected peak-week of cholera in the area (peak survey, urban site) and at the end of the expected cholera season (post-season survey), as compared to baseline or pre-season survey.
3. To assess the intra-household transmission and correlation in cholera recent infections among vaccinated and non-vaccinated households (post-season survey)
4. To compare mortality linked to diarrheal diseases and potential cholera in the community of rural site before and after vaccination
5. To assess the duration of shedding among vaccinated and unvaccinated individuals and the duration of viable V. cholerae in the peri-household environment.
6. To measure the secondary cholera attack rates (symptomatic and asymptomatic) at household level among vaccinated and unvaccinated individuals following the identification of an index case in a given household.

Eligibility criteria: Inclusion Criteria:

* All persons,

  1. Living in the randomly-selected households in targeted area AND
  2. Randomly selected among household members. Inclusions will be limited to 1 participant per household, except for one survey AND
  3. Giving his/her consent (or assent for children 13 to 17 years old) to participate in the study

Exclusion Criteria:

* People who decline to participate will be excluded from the study. For 2nd survey in Goma only: members of the household who cannot be reached after 2 attempts will be excluded.

Primary outcomes:
measure: To better characterize cholera immunization in the population of cholera hotspot in Africa and assess the impact of a large vaccination campaign reaching high coverage
timeFrame: 2 years
Secondary outcomes:
measure: Calculate proportion of individuals infected with cholera (previous year or last 2 months) before the campaign distribution or in non-vaccinated zones or following the massOCV campaign and before the start of cholera season:pre-season survey, urban site.
timeFrame: 2 years
measure: Assess proportion of individuals infected (the last 2 months or previous year) during the expected peak-week of cholera in the area and at the end of the expected cholera season (post-season survey), as compared to baseline or pre-season survey.
timeFrame: 2years
measure: To assess the intra-household transmission and correlation in cholera recent infections among vaccinated and non-vaccinated households (post-season survey)
timeFrame: 2 years
measure: To compare mortality linked to diarrheal diseases and potential cholera in the community of rural site before and after vaccination
timeFrame: 2 years
measure: To assess the duration of shedding among vaccinated and unvaccinated individuals and the duration of viable V. cholerae in the peri-household environment.
timeFrame: 2 years
measure: To measure the secondary cholera attack rates (symptomatic and asymptomatic) at household level among vaccinated and unvaccinated individuals following the identification of an index case in a given household.
timeFrame: 2 years
Other outcomes:
Locations:
city: Bukama
country: Congo, The Democratic Republic of the
facility: Epicentre/Médecins Sans Frontières
state: Haut-Lomami
city: Goma
country: Congo, The Democratic Republic of the
facility: Médecins Sans Frontières France
state: Nord Kivu
Study officials:
affiliation: Epicentre
name: Klaudia Porten
role: STUDY_DIRECTOR
affiliation: Gavi
name: Francisco Luquero
role: STUDY_CHAIR
References: