Ebola faces vaccine triple threat

The ongoing West Africa Ebola epidemic, which has severely plagued countries such as Sierra Leone, Liberia and Guinea for almost a year, has already claimed the lives of more than 8,300 people and affected nearly 22,000 others.

Those who are infected with Ebola develop fever, headache, and joint and muscle pain. The initial infection is then followed by diarrhoea, stomach pain, internal bleeding and, in many cases, death.

“The plans are advanced for a large Phase 3 trial which will begin early this year in Liberia

GSK spokesman

It is thought that the current Ebola epidemic was originally transmitted from fruit bats to humans, who then inadvertently spread the virus thorough direct human-to-human contact with an infected person’s bodily fluids, and via surfaces and materials contaminated with such fluids.

There are, however, a variety of measures currently being deployed to help stop the spread of infection, with African nations such as Senegal and Nigeria employing these measures to completely eradicate the spread of infection.

Experts are working tirelessly in the most affected areas to help contain Ebola, and assist those countries where the virus has rampaged most severely.

“The increased deployment of resources to fight [the] Ebola virus in the most affected countries seems to be paying dividends,” says Jonathan Ball, professor of molecular virology at the University of Nottingham.

“We should never forget the importance of effective infection prevention and control in stamping out this outbreak, but we are certainly not out of the woods yet,” he says.

To complement these efforts, several pharmaceutical companies are developing Ebola vaccines - many of which are currently being trialled in clinical studies.

There are, essentially, three frontrunners in the race to create the world’s first widely available Ebola vaccine.

Perhaps ’least likely’ to ’win the Ebola vaccine race’ is US pharmaceutical firm Johnson & Johnson (J&J).

The J&J vaccine consists of a prime, which stimulates initial immune response, followed by a boost intended to further enhance the level of the body’s immune response over time. The vaccine regimen developed by J&J does not contain any replicating virus, so it is not possible to be infected with Ebola.

According to J&J, a total of 2 million regimens of the prime-boost vaccine will be available this year, with trials currently being conducted in 72 healthy adults by scientists at the University of Oxford’s Oxford Vaccine Group.

Prior to these initial Phase 1 clinical trials, the vaccine had successfully been administered to non-human primates in pre-clinical studies, who exhibited complete protection from death.

Secondly, and perhaps most likely to succeed in developing a widely available Ebola vaccine this year is the GlaxoSmithKline (GSK)/ National Institutes of Health’s (NIH) vaccine which has been successfully trialled in 20 volunteers, and which is now going to be trialled in Ebola-affected countries.

“The plans are advanced for a large Phase 3 trial which will begin early this year in Liberia and which will be run by the NIH,” a GSK spokesman says.

The spokesman also says GSK is hoping to work alongside the Centers for Disease Control (CDC) to conduct a clinical trial in Sierra Leone, but that trial is yet to be confirmed.

In addition to its Phase 3 trial(s), GSK also hopes to conduct Phase 2 trials in non-affected countries such as Cameroon, Ghana, Mali, Nigeria and Senegal…”where the efficacy and safety of Ebola vaccine candidate (ChAd3) will be further accessed”.

“We have submitted information to the regulatory authorities in these countries. Assuming there [is] no further information required, these Phase 2 trials should begin in February,” the spokesman says.

Arguably falling just shy of GSK’s progress is the rVSV-EBOV vaccine candidate currently being co-developed by genetics firm NewLink and US pharmaceuticals giant Merck.

During December last year, Merck and NewLink announced that they had been awarded $30 million (£19.8m) by the Biomedical Advanced Research and Development Authority, US to help support the development and manufacture of the rVSV-EBOV vaccine, including clinical development via a 330-person Phase 1 study.

“This vaccine is still experimental and efficacy and safety in preventing Ebola disease is still unknown,” says Mark Feinberg, chief public health and science officer, Merck Vaccines.

“Once appropriate data are available, Merck will work to expedite submitting data to regulatory agencies to make the vaccine available to as many people at risk of Ebola virus infection as possible.”

For Feinberg, one of the main challenges faced in getting an effective Ebola drug to market is advancing the development of the vaccine in a rigorous and scientifically and ethically sound manner as quickly as possible.

“There are additional issues such as protection of vaccine manufacturers from liability claims in the course of the clinical studies and early introduction efforts,” Feinberg says.

“While some progress has been made in this area, additional efforts are needed.”

“This vaccine is still experimental and efficacy and safety in preventing Ebola disease is still unknown

Mark Feinberg, Merck Vaccines

To unify the life-saving potential that could be delivered by each of the three vaccines mentioned above, and the variety of other Ebola treatments currently being developed, healthcare foundation The Wellcome Trust is set to launch a roadmap for “the expedited development, testing, manufacture, delivery and financing of Ebola vaccines”.

“As Guinea, Liberia and Sierra Leone make encouraging progress in containing Ebola, we must not lose sight of the immense contribution that a safe and effective vaccine would make towards controlling both this and future epidemics,” says Jeremy Farrar, director of the Wellcome Trust.

“We need urgent global collaboration between governments, industry and philanthropy to ensure candidate vaccines progress through trials to manufacture and delivery as swiftly as possible.”

According to Farrar, a draft roadmap, published earlier this month, offers solutions to the scientific, social, logistical and financial challenges of delivering an Ebola vaccine on an urgent timescale.

“It is a living document that will evolve as we learn more about Ebola and the candidate vaccines that are available. As well as being of great value in the present crisis, it will enable vaccine strategies to begin without delay in future outbreaks, and provide a model for vaccine development in response to other emerging infectious diseases,” Farrar says.