Impact evaluation of OCV preventive campaigns, DRC

Main objective

To better characterize cholera transmission in cholera hotspot in DRC and assess the impact of a large vaccination campaign reaching high coverage on sustained control of cholera transmission for at least two years.

Methods

Clinical surveillance (Goma and Bukama)
Observational surveillance study at CTC/CTU level, including all patients in all active structures of the zones (ZS Goma, Karisimbi, Nyiragong, Kirotshe and ZS Bukama). Systematic RDT testing, questionnaire, collection of dry and humid filter papers

Seroprevalence surveys (Goma and Bukama) – collecting venous blood samples
Goma: 6 serosurveys at different time of the year (all post-vaccination). Bukama: 3 serosurveys once a year (1 before vacci, then 1 and 2 years after), + mortality survey

Home follow-up (Goma only)
Repeated home visits for RDT positive cases (D1, D4, D7, D14, D28, D90 and D180). Stool testing from the family, questionnaire, collecting environmental samples.

Evaluate the impact of OCV preventive campaigns at different levels:

• Impact on number of cholera cases: symptomatic cases in CTC/CTUs
• Impact on transmission in the community: monitoring level of immunity in the population including asymptomatic cases
• Impact on transmission at household level

This study will help us better understand the impact of mass cholera vaccination programs to set expectations for decision makers and help understand when revaccination may be needed.