Although tremendous progress has been made in Ebola vaccine development in the last two years, the latest report by Wellcome and the University of Minnesota's CIDRAP Ebola Vaccine Team B says without renewed commitment from the global public health community, progress towards approved vaccines for Ebola could grind to a halt as memories of the outbreak in West Africa begin to fade.
During the 2014–2015 epidemic, a total of 13 Ebola vaccine candidates (including different combinations of vaccines) were evaluated in phase 1 and/or phase 2 clinical trials and three phase 3 efficacy trials were initiated in Africa – one each in Guinea, Liberia, and Sierra Leone.
Vaccine manufacturers, such as Johnson & Johnson and GSK, have advanced their respective Ebola candidate vaccines well into the clinical trial process. Trials of one vaccine, Merck's rVSV-ZEBOV, have progressed far enough to demonstrate that it is safe and effective, prompting GAVI, the vaccine alliance, to purchase 300,000 doses as a stockpile for use during future Ebola outbreaks.
However, to date, no vaccine has been submitted for regulatory review and many questions regarding Ebola vaccines remain unresolved. Today's report from the Ebola Vaccine Team B identifies four main areas where work is still needed before the world is fully prepared for another Ebola outbreak:
- Filling in the gaps in data on the safety and efficacy of Ebola vaccines
- Understanding the complex regulatory pathways for Ebola vaccines
- Gaining direct input from African public health leaders to clarify how Ebola vaccines will be used or evaluated in respond to future Ebola outbreaks
- Creating a business case for ongoing Ebola vaccine development and deployment.
The group outlines recommendations for how each of these can be achieved, including completing clinical trials of vaccine candidates to fill in the missing gaps in data, and being ready to run both phase 3 efficacy studies and phase 4 post-marketing studies from the start of the next Ebola outbreak.
Wellcome Trust Director Dr Jeremy Farrar, who co-chairs Ebola Vaccine Team B, said: "Although a global collaborative effort has moved us from having no drugs or vaccines in the early days of the Ebola epidemic to now having a safe, effective vaccine, and other promising candidates, it has taken too long, and the job is still not done.
"As Ebola infection rates come under control it’s a huge concern that complacency sets in, attention moves to more immediate threats, and Ebola vaccine development is left half-finished. Today we're calling for a renewed commitment from the global health community. After the hard lessons we've learned, it would be a tragedy not to put a final stop to the current Ebola epidemic, and be prepared for the next outbreak."
Co-chair, and Regents Professor and Director of CIDRAP, Dr Michael Osterholm added: "While many in the international public health community believe these efforts have solved 'the problem of Ebola,' the path forward is not quite so simple, and many unresolved challenges and questions remain. In our report, we identify the key areas in which critical additional work and effort are needed to enhance Ebola preparedness for future outbreaks, particularly in the megacities of equatorial Africa, and to address the ongoing concern that Ebola virus disease may become endemic in West Africa."
This report from Team B follows a report published in February 2015, which set out a framework for developing vaccines for Ebola, and increasing preparedness for emerging infectious diseases. It can be downloaded from the CIDRAP website.
The group is called 'Team B' in recognition of the principal role played by the World Health Organization and national governments in leading the international Ebola response.