World Health Organization expedites trials for potential Ebola vaccines

The World Health Organization has announced that two vaccines will be expedited to clinical trials and could be available as soon as November 2014 for priority use in healthcare workers.

Ebola volunteer health workers

As criticism mounts over the slow response to the most serious outbreak of Ebola in West Africa, the World Health Organization (WHO) announced that two vaccines will be expedited to clinical trials and could be available as soon as November 2014 for priority use in healthcare workers.

After consulting more than 200 virologists, regulators and policymakers, WHO deems that the use of blood therapies and convalescent blood serum also needs to be considered a matter of priority.

WHO has also recommended the pursuit of experimental drugs, including monoclonal antibodies, RNA-based drugs and small antiviral molecules.

“One of the things driving fear and panic is the belief that there is no treatment for Ebola virus disease,” Marie-Paule Kieny, the WHO’s assistant director-general for health systems and innovation, said. “Tremendous work is being done to accelerate our knowledge of potential Ebola intervention and give us some promising tools.”

Kieny said the two leading vaccine candidates prioritised for clinical development were chimpanzee adenovirus Ebola (cAd3) and vesicular stomatitis virus (VSV). Safety studies are being conducted in the United States and are soon to start in Europe and Africa.

The cAd3 vaccine is made by GlaxoSmithKline (GSK) and VSV vaccine by NewLink Genetics Corp.

According to WHO, the cAd3 vaccine has been tested in non-human primates with promising results, but it is not known whether the vaccine will protect humans from the Ebola virus, and if it does, for how long the effect would last.

Similarly, phase I clinical trials of the VSV vaccine will be performed on healthy individuals, and will be too small to detect uncommon adverse events associated with the vaccine.

“Safety results may be available in November 2014,” said Kieny. “This would open the way for use in affected countries, initially on healthcare workers and other front line staff as advised by the ethics panel that met recently to look at the ethics of use of these medicines against Ebola.”

Kieny said 10,000 doses of the cAd3 vaccine might become available at the end of the year, and for VSV, she noted, the Canadian government has made a donation of 800 doses.

Loss of healthcare workers is compounding the risk of spread

The death toll is reckoned to have passed 2,000, and the loss of healthcare workers severely compounds the risk of spread. “When the outbreak began, Liberia had only one doctor to treat nearly 100,000 people in a total population of 4.4 million people. Every infection or death of a doctor or nurse depletes response capacity significantly,” a WHO statement said. “Many thousands of new cases are expected in Liberia over the coming three weeks.”

Samba Sow, director-general at the Centre for Vaccine Development in Mali, said in some affected countries, such as Liberia, 10% of the health workers are dying. “Health workers now are scared to come to the health centres and take care of patients. So, health workers, if you vaccinate them that will help them.”

Sow told The Pharmaceutical Journal his centre will participate in the vaccine development, jointly with the University of Oxford Jena Institute and the University of Maryland Center for Vaccine Development.

The WHO’s Kieny said there was also discussion on the experimental therapy ZMapp — a cocktail of three chimeric mouse-human monoclonal antibodies — but she noted “there is not enough experience with ZMapp to conclude whether this treatment works or not, although there seems to be encouraging signs that it would work”.

Kieny noted the medicines regulators’ unprecedented willingness to move quickly. “They are really helping us in order to facilitate processes, while trying to preserve — as much as possible — safety.”

Although hastening of action by the WHO has been welcomed, there has been growing criticism that the response has been too slow. Lawrence Gostin, director of the O’Neil Institute for National and Global Health Law at Georgetown University, told The Lancet that WHO had been too slow to implement an Ebola action plan, which was ushered in five months after the outbreak began. He also highlighted the failure by the agency, due to lack of sufficient financial commitments by rich countries, to set up a proposed Global Emergency Workforce, as recommended in 2011 by a review committee.

Asked to respond to Gostin’s remarks, Margaret Harris, a WHO spokeswoman, told The Pharmaceutical Journal: “We have been able to tap into the global outbreak alert and response network (GOARN) to find people with the right expertise. However, the skills, equipment and training needed to respond to an Ebola outbreak of this size and complexity are in scarce supply.

“Ebola is a rare disease (usually) so few people have specialist Ebola training or skills. People who began working on this outbreak months ago are now exhausted and need replacing.” 

Last updated
The Pharmaceutical Journal, PJ, 20 September 2014, Vol 293, No 7828;293(7828):DOI:10.1211/PJ.2014.20066400

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