Marie-Paul Kieney, Assistant Director-General for Health Systems and Innovation, said at least eight candidates are in development and enough doses will be available for mass inoculations in West Africa in the first half of 2015.
GSK, NewLink, and beyond
Phase I studies have begun on the two most advanced Ebola vaccine candidates so far: GSK’s cAd3-ZEBOV (chimpanzee adenovirus type-3 vector; and VSV-EBOV (which is based on the vesicular stomatitis virus), discovered in Canada and trialled by NewLink. Both express glycoproteins of the Zaire virus strain (ZEBOV), or the closely related Marburg filovirus.
Safety data are expected in December 2014.
To speed up development, efficacy trials – usually part of Phase III – will begin early for the GSK and NewLink candidates – as soon as December 2014, said Kieney: “Of course protocols will be adapted to taken into account safety and immunogenicity results of the Phase I trial as they become available.”
The WHO said at least five more experimental vaccines are “following closely” and will be in the clinic in January 2015. Crucell, Profectus BioSciences, J&J, Bavarian Nordic and Novavax have all announced they are developing candidates.
Additionally, Russia revealed an eighth potential vaccine to the WHO meeting – an adenovirus-based candidate, like GSK’s and J&J’s, based on a lentiviral vector from a naturally attenuated strain of the flu virus.
So far, trials are taking place in the US, UK and Mali, said Kieney, with others due to begin soon in Switzerland, Germany, Gabon, and Kenya. The countries most severely affected – Liberia, Sierra Leone, and Guinea – are also being considered under “advanced” plans, possibly beginning in Liberia among frontline workers.
Production: leaked docs
All the pharma companies are committed to ramping up vaccine production capacity to millions of doses in 2015, with quantities in the hundreds of thousands (“maybe 200,000”) likely ready in the first half of next year, said Kieney.
But scaling up production on a massive scale brings challenges.
In leaked documents seen by the journal Science, GSK said filling capacity is a “critical issue” and it lacks enough facilities to manufacture in BSL-2 (biosafety level 2) conditions, noting that if it fills in-house, the Ebola vaccine will take up capacity usually reserved for other vaccines.
Kieney said that while the WHO has “no opinion” on the wisdom of downgrading Ebola vaccines from BLS-2 to BSL-1, the question is being urgently studied by regulators, with the co-ordination of the Director-General.
“To make this a reality, regulatory authorities in countries where the vaccine is manufactured as well as in Africa will need to work closely with manufacturers under extremely short timelines to find ways to overcome a number of hurdles in the licensing regulation of these vaccine,” said Kieney.
“Community engagement will be key. Work should be scaled up urgently in partnership with local communities, national governments, NGOs and international organisations to have this happen.”