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NEW STUDY: Rabies vaccine trial gets underway in Tanzania - a collaboration between Ifakara and Oxford

March 4, 2022
NEW STUDY: Rabies vaccine trial gets underway in Tanzania - a collaboration between Ifakara and Oxford
This is the Ifakara Clinical Trials Facility at Kingani area in Bagamoyo, which is hosting the trial. PHOTO | IFAKARA/FILE

Ifakara Health Institute yesterday launched trial for a novel rabies vaccine in human volunteers in Tanzania. The trial is conducted in collaboration with the University of Oxford, which had produced the vaccine and tested it for the first time in the UK.

This particular trial in Tanzania builds on encouraging results from a recent, smaller study of the same vaccine in the UK. An estimated 192 healthy people will be randomly assigned to receive one dose of the Oxford vaccine, or one or two doses of a currently licensed rabies vaccine.

Rabies causes about 50,000 deaths every year, mostly in Asia and Africa (more than 1500 deaths annually in Tanzania) and it’s the only known viral infection with essentially 100% fatality. The vaccine, known as “ChAdOx2 RabG” have the potential to induce protective immune responses with a single dose compared to other existing vaccines.

The vaccine has been designed to be used in a single-dose regimen. This will have a significant impact on the vaccine roll-out, unlike currently approved human vaccines which are relatively expensive and require repeated dosing, limiting their use where they are needed most.

In reaction to the ground-breaking announcement, Dr. Ally Olotu of the Ifakara Health Institute and Principal Investigator of the trial said, “Rabies causes more than 1500 deaths annually in Tanzania and imposes a significant financial burden to the poorest in the community who require PEP and supportive treatment following a bite with a rabid animal.”

Dr. Olutu, currently Head of the Interventions and Clinical Trials department at Ifakara, commends the development of vaccines that are cheaper and require less encounter with health facilities and which can reduce inequities and facilitate compliance. He added that “This study will generate important data on the safety and ability of the candidate vaccine to induce effective immune responses and their duration in an endemic population.”

“Ifakara Health Institute has a long track record of evaluating health innovations that aim to improve people’s health and well-being. We are happy to work with the University of Oxford on this important study.” Dr. Olutu expressed the Institutes’ delight in being part of the development of the rabies vaccine.

From the University of Oxford, Dr Sandy Douglas, Research Group Leader and Chief Investigator of the trial commented on the collaboration saying, “Rabies really should be consigned to history. It’s a privilege to work with such an expert team of African scientists to develop a new, modern tool to fight this terrible disease.’

“Many people are unaware that rabies still kills about 50,000 people every year, mostly in Asia and Africa – it’s the only known viral infection with essentially 100% fatality. Current rabies vaccines are effective but they require multiple doses and they’re too expensive for broad use. A single-dose, low-cost vaccine would be a game-changer – this trial should show us whether our new vaccine could provide that,” she said.

Ifakara’s previous involvement in rabies vaccination development and evaluation
In 2011 and 2019 conducted a study on reservoir dynamics of rabies in south-east Tanzania and the roles of cross-species transmission and domestic dog vaccination. The study was plotted within the 13 districts of the Lindi and Mtwara regions of south-east Tanzania, which were part of a World Health Organization (WHO) coordinated demonstration project funded by the Bill and Melinda Gates Foundation to pilot strategies for rabies control and elimination.

Conclusions from the study indicated the effectiveness of dog vaccination in reducing exposure risks in humans and decreasing rabies incidence among all species. More focus on dog vaccination could have major public health benefits, and if sustained and coordinated could eliminate RABV, the study found. Ifakara researchers also recommended ongoing effective surveillance saying it is essential to monitor the impacts of dog vaccination in order to reach the ‘Zero by Thirty’ target.

Later in May 2021, Ifakara and seven other partners launched the national rabies vaccination campaign in Kisarawe district which was taken to other districts in Tanzania later that year. Africa One Health University Network (AFROHUN) – an organization training the next generation workforce that will face outbreaks of epidemics, pandemics and complex health challenges globally – leads the initiative. The Ifakara team was assigned to lead the data collection work package and conduct a post-vaccination evaluation survey afterwards.

More about the Phase Ib/II trial testing (RB002 Trial)
One year after receiving the candidate rabies vaccine ChAdOx2 RabG, all participants in the RB002 trial will receive two currently licensed rabies vaccine doses. The licensed rabies vaccine doses will offer all study participants robust protection against rabies, regardless of how well the Oxford vaccine works.

From the findings, the study will show whether the new vaccine creates strong immunological ‘memory’ which can then be ‘recalled’ quickly by a further vaccination. This recall would be important to provide robust protection in the event of exposure to rabies.

Following the vaccination, all participants will be monitored closely through several visits over 18 months. Initial results from the recently completed UK trial will be published soon and initial results from the new study in Tanzania should be expected later this year, with full results in late 2023.