Finding a way to help African citizens recover from Cholera: the best way possible

Health & research

Jan 26

Who: Doctors Without Borders

What: Cholerastudy

Where: International

Project period: 2020 – 2021

Web: Doctors Without Borders

Cholera is a bacterial infection of the intestine, caused by the bacterium Vibrio cholera, which leads to profuse watery diarrhoea. If left untreated, cholera can kill a person very quickly. Every year an estimated 3 million cholera cases and about 100,000 deaths occur worldwide but the global burden of cholera is unknown because the majority of cases are not reported.

Cholera is endemic in many parts of the world (more than 50 countries mostly located in Africa) and is a disease of poverty, closely linked to poor sanitation and a lack of clean drinking water. Area particularly at risk include slums, inadequate and overcrowded camps, conflict zones, aftermath of natural disasters and any other area affected by humanitarian emergencies in endemic countries.

While oral cholera vaccines (OCV) have proven effective in preventing cholera during outbreaks, current two-dose strategies are logistically challenging to implement. To carry out two rounds of mass vaccination within two weeks is not always feasible during emergencies where a prompt and reactive response is need and where thousands of people should receive the vaccine in area sometimes of limited access and in the context of mobile population. In many campaigns implemented to date, the second dose has been administered using a longer interval. As such, it is important to understand the potential implications of an increased dosing interval for protection.

To guide and provide more flexibility and operational possibilities to future OCV vaccination campaigns and to improve cholera prevention, Grieg Foundation funds a study conducted by MSF and Harvard University to find out if the immune response of an extended interval (6 or up to 12 months) between OCV doses is at least as good as the immune response to the vaccine administered according to manufacturer instructions (two weeks).

The results of such study results might potentially lead to a re-labelling of OCV for use with longer interval and hence, to a revision of WHO recommendations. This would have a huge operational impact as it would affect all MSF projects located in cholera endemic countries. They would also have important implications for practice and policy on cholera control strategies at national and international level over the world.

The study will be an open-label, randomized, controlled, non-inferiority immunogenicity trial. In short, eligible healthy participants aged 1 to 40 year-old will be recruited in the general population of the commune of Dixinn (Conakry, Guinea). All participants who voluntarily consent to participate will be randomly allocated in three groups of 142 persons each. Each group will receive the vaccine according to a different schedule: second OCV dose given either 14 days, or 6 months or 1 year after the first dose. The OCV administration will be followed by several follow-up visits up to 6 months after having received the second dose (the follow-up will thus last up to 18 months for the study group receiving the second OCV dose 12 months after the first dose). At each visit, blood will be drawn to measure various indicators of immunity resulting from vaccination (immunologic analyses conducted in Conakry and in Harvard University, US). A non-inferior immune response will be interpreted as an indication that the longer interval between doses can be considered an alternative to the currently recommended 14-day interval.

The study will last for 2 to 3 years. The study will be conducted in accordance with the international ethical standards as stated in the Declaration of Helsinki and following the requirements of Good Clinical Practice (GCP) regulations.