Extended dosing schedules for the oral cholera vaccine in Kenya
A Phase IV Parallel-Group, Open-Label, Randomized Non-Inferiority Trial Evaluating Immunogenicity of Extended Dosing Intervals for Euvichol-S Oral Cholera Vaccine, Nairobi, Kenya
This tests whether giving the Euvichol-S oral cholera vaccine with longer gaps between doses (2 months or 12 months instead of the standard 2 weeks) produces a similar immune response in people aged 1 year and older in Mukuru, Nairobi.
Quick facts
| Phase | Phase 4 |
|---|---|
| Study type | Interventional |
| Enrollment | 1071 (estimated) |
| Ages | 1 Year and up |
| Sex | All |
| Sponsor | Albert B. Sabin Vaccine Institute Academic / other |
| Locations | 1 site (Nairobi) |
| Trial ID | NCT07487077 on ClinicalTrials.gov |
What this trial studies
This Phase IV, open-label, randomized non-inferiority trial will enroll 1,071 participants in Mukuru, Nairobi and randomly assign them to one of three parallel groups receiving two doses of Euvichol-S separated by 2 weeks, 2 months, or 12 months. Participants are stratified into three age groups (1–4, 5–14, 15+ years) to compare immune responses by age. The primary endpoint is the plasma vibriocidal geometric mean titer measured two weeks after the second dose, with longer follow-up to evaluate durability. The trial is led by the Albert B. Sabin Vaccine Institute in collaboration with KEMRI, Washington State University, and Massachusetts General Hospital.
Who should consider this trial
Good fit: Ideal candidates are residents of Mukuru, Nairobi aged 1 year or older who are generally healthy, can provide informed consent or assent, and can attend scheduled follow-up visits.
Not a fit: People with serious uncontrolled illnesses, contraindications to the vaccine, or those who do not live in the study area or cannot complete follow-up visits are unlikely to benefit from participation.
Why it matters
Potential benefit: If successful, longer dosing intervals could allow more flexible, wider vaccination campaigns while maintaining similar immune protection.
How similar studies have performed: Oral cholera vaccines including Euvichol-S are proven to prevent cholera, but evidence specifically supporting extended dosing intervals is limited and not yet conclusive.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Residents of Mukuru, Nairobi, Kenya * Individuals aged 1 year and above * Voluntary written informed consent for study participation provided by an individual or his/her legally acceptable representative. Children aged 13 years and above will also provide assent, with parental permission required for all children. * Ability to comply with study requirements and attend follow-up visits during the study period. Participants must be in good health, as determined by medical history, physical examination, and the clinical judgment of the investigators. Clinical judgment will consider factors such as the absence of acute illness or, uncontrolled or severe chronic conditions that may affect participation in the study. * Lactating women may be enrolled following clinical assessment and informed consent. The vaccine contains killed, formalin-inactivated bacteria that are not systemically absorbed and act locally in the gastrointestinal tract. Exclusion Criteria: * Known history of hypersensitivity reactions to other vaccines. * Pregnant women, due to differences in immune response. A pregnancy test will be administered to all female participants who have reached menarche and are under 50 years. * Reported diarrhea or abdominal pain lasting 2 weeks or longer within 6 months prior to study initiation; to avoid confounding the vaccine's effects with pre-existing conditions. * Received a cholera vaccine in the last 24 months: Ensures that the study assesses the vaccine in question without interference from prior vaccinations. * History of cholera disease in the last 24 months: Recent history of cholera infection can interfere with the measurement of vaccine response. * Severely malnourished individuals as determined by mid-upper arm circumference (MUAC) and age-specific body mass index (BMI) measurements: malnutrition can affect immune response and vaccine efficacy. In children below 510 years, severe malnutrition will be defined as MUAC \< 11.5 cm, for older children (age 5 - 17y) severe malnutrition will be defined as BMI-for-age z score \< -3 (WHO Child Growth Standards), for children \<10y, presence of bilateral pitting oedema will be considered indicative of severe malnutrition. For adults (18y and above), severe malnutrition will be while in older children and adults it will be defined as BMI \< 16. * Non-HIV/AIDS immunosuppressive condition or on immunosuppressive therapy: Such conditions can significantly alter vaccine response. * Presence of bleeding disorders or medical contraindication for blood draws: To ensure participant safety during blood collection. * Participation in another clinical trial with investigational product dosing within 6 months prior to study initiation. * An individual thought to have difficulty in participating in the study due to severe chronic diseases, based on the judgment of the investigator. * An individual thought to have difficulty participating in the study due to reasons, such as significant logistical constraints, or communication barriers, or likely to be away for a period of at least 3 consecutive months in the first 6 months of enrollment based on the judgment of the investigator.
Where this trial is running
Nairobi
- Kemri — Nairobi, Kenya (Recruiting)
Study contacts
- Study coordinator: Samuel Kariuki, BVM, PhD
- Email: samkariuki2@gmail.com
- Phone: +254 722232467
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.