Drugmakers sprinting to develop Ebola vaccines face a series of technical hurdles if they are to get millions of doses ready for use next year — even assuming clinical trials are successful.
Development is gaining momentum, with the World Health Organization expects vaccine efficacy trials to start in West Africa in December, a month earlier than anticipated.But industry executives, health experts and governments are still grappling with a host of issues – and some differences of opinion – on topics ranging from clinical trial design to factory biosafety levels, according to people who attended a high-level meeting of officials in Geneva last week.
"There is not a funding problem," said one person at the meeting. "The real issues are all around the practicalities."
Two leading vaccine candidates from GlaxoSmithKline and NewLink Genetics are already in human safety trials, and another five should begin testing in the first quarter of next year. One from Johnson & Johnson will start trials in January.
Translating bulk vaccine production into vials of product ready for widespread use in Liberia, Sierra Leone and Guinea, where the disease is still spreading rapidly, needs a massive packaging effort.
"One of the main bottlenecks is filling capacity," said WHO assistant director general Marie-Paule Kieny.
Because Ebola vaccines use genetically modified organisms, the sterile filling of vials must be done in a so-called biosafety level 2 (BSL2) facility, which only a few companies possess.
Those with BSL2 operations include GSK, Sanofi, Merck and Novartis, but in many cases their factories are already working on other important vaccines against diseases such as measles, mumps, rubella and rotavirus.
Another hurdle that must be overcome is accelerating the quality approval process required by regulators for finished vaccines, which typically involves lengthy checks at various stages in the production process.
The hope is to run some quality checks in parallel, rather than sequentially. That will require the buy-in not only of regulatory authorities in producing countries but also those in Africa to prevent consignments being delayed at customs.
Further down the road, the final piece that needs to be put in place is a system for procuring and delivering the millions of vaccine doses that may be ready for deployment later in 2015, through a supply chain that will need specialist refrigeration.