Non- Inferiority Fractional-doses Trial for Yellow Fever Vaccine
Kenya, Uganda900 participantsStarted 2019-11-11
Plain-language summary
In the recent past there has been a number of large urban Yellow Fever outbreaks in sub-Saharan Africa, tropical South Americas, The demand for Yellow Fever vaccines in response to the large urban outbreaks occurring concurrently and the risk of further spread through Africa and to Asia was larger than the available global supply. In this situation, the World Health Organisation (WHO) developed recommendations for the use of fractional doses of Yellow Fever vaccine as a dose-sparing strategy. These recommendations were based on data from a limited number of clinical trials, none of which had been conducted in Africa. This was due to the uncertainties on the minimum dose requirement.
Our study complements a study which is comparing full standard dose to 1/5th of standard dose of all four WHO-prequalified YF vaccines in adults (ClinicalTrials.gov number: NCT02991495), and is currently ongoing at KEMRI CGMRC and Epicentre, Mbarara which is designed to answer questions on the use of current stock of YF vaccines with a potency as close as possible to each manufacturers' minimum release. Data from this trial will inform a WHO recommendation on using 1/5th of the current standard dose of vaccine for outbreak control. However, since many vials will contain excess YF vaccine such that 1/5th of a vial is likely to be substantially above the current minimum potency requirements, these data may not be scientifically explanatory regarding the minimum dose required for preventive use.
The new complementary study, aims to determine the lowest YF vaccine dose that is non-inferior to the current standard full dose among populations in sub-Saharan Africa. The study will be conducted in Kenya (KEMRI Center for Geographical Medicine Research-Coast (CGMR-C), Kilifi) and Uganda (Epicentre, Mbarara) with trial participants recruited at both sites, using vaccine from one WHO-prequalified manufacturer (Institut Pasteur de Dakar, Senegal (IPD)).
Who can participate
Age range
9 Months – 59 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* Individuals aged ≥18 - \<60 years of age.
* Children aged between 9 months and 12 months.
* HIV negative on serological screening OR HIV positive adults and children aged \> 18 months on serological testing, and no symptoms suggestive of current clinical immunosuppression and cluster of differentiation-4 (CD4) count\>200 (for adults) and CD4% \> 25% (for children aged 9-12 months) within the last 6 months.
* Ability to provide informed consent to participate in the study
Exclusion Criteria:
* Known contraindications to YF vaccination such as allergies to egg protein and chicken products or any component of the vaccine (including gelatin, eggs, eggs products or chicken products), immunodeficiency, known thymus disorder, such as thymoma and myasthenia gravis
* Using corticosteroids or other immunosuppressive therapy
* Thymus disorder, such as thymoma and myasthenia gravis
* Acute febrile disease on the day of vaccination with temperature \>37.5 degrees Celsius is a temporal contraindication.
* Previous YF vaccination
* Previous YF infection as determined from history
* Pregnancy (as determined by a urine test on the proposed day of vaccination) and lactating women
* Planning to migrate out of the study areas before the end of the study follow-up
* Planning to travel to a country requiring YF vaccination certificate within the first year after vaccination.
* Any condition or criteria, including acute or chronic clinically significant abnormality that in …
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
The proportion of vaccinees that seroconverts as measured by Plaque Reduction Neutralisation Test (PRNT-50)