Two Ebola vaccines for health care workers expected as soon as November

An expert group of technicians working on developing Ebola interventions suggested last Friday that two of the most advanced vaccines could be made available to health workers in November this year, provided they are proven safe.

Safety studies for these vaccines – based on vesicular stomatitis virus (VSV-EBO) and chimpanzee adenovirus (ChAd-EBO) – are currently being conducted in the United States and will be started in Africa and Europe by mid-September.

“WHO will work with all the relevant stakeholders to accelerate their development and safe use,” announced a spokesperson to the media on Friday evening at the Geneva headquarters.

The announcement followed a two-day consultation with more than 150 participants from fields of research and clinical investigation, ethics, legal, regulatory, financing, and data collection. The consensus was that as existing supplies of all the experimental medicines are limited – and there wouldn’t be sufficient supplies for at least several more months – the prospects of having vaccines available “look slightly better.” Among other possible measures, use of survivors' blood was also suggested as an alternative treatment plan.

The vaccines

According to a background document prepared by the WHO ahead of the consultation, more than 1,300 people in parts of Africa have received the chAd3 vaccine for other diseases safely, but it hasn’t been tested for Ebola on humans yet. It is possible to obtain about 15,000 doses of the vaccine later this year.

The vaccine comes from a chimpanzee adenovirus, and a single dose has protected animals from a lethal dose of the Ebola virus in the past, according to the WHO. Human trials will be conducted in the US this month, followed by UK and some African countries.

Meanwhile the rVSV vaccine has been found to protect animals from the Ebola virus, after it was injected directly into their brains. The vaccine “aims to induce Ebola virus disease-specific immune responses,” according to the WHO memo, and is yet to be assessed to be safe for humans.

This vaccine was successfully given to one laboratory worker several years ago, according to the WHO, after exposure to the Ebola virus. However this “does not prove the vaccine will be safe or protective,” and an early trial will be conducted in the US now to check its effectiveness on humans. Around 800 doses of this vaccine are already available.

The challenges

While efforts to evaluate and produce the vaccines are in full speed, safety of these two vaccines in humans is unknown, and a possibility of adverse side effects cannot be ruled out, besides questions on their actual efficacy. For this, WHO has identified several precautions that will need careful monitoring. These include creating a platform for transparent, real-time collection and sharing of data as well as the establishment of a safety monitoring board to evaluate the data from all interventions.

Meanwhile, if found safe, these vaccines would also need proper infrastructure such as safely storing and transporting them in controlled temperatures before injecting them, which is already a challenge in some parts of Africa. They also need intravenous administration, which would mean adequate expertise in personnel who will be doing the vaccinations.

Lack of funding is a major source of worry for the much-needed infrastructural support in combating the outbreak. The United Nations recently announced that at least $600 million in funding is required for getting medical supplies to the affected West African countries. Meanwhile, the White House has requested for $88 million to fight Ebola.

The WHO’s Ebola response roadmap identifies at least $490 million needed immediately – an estimate that could change as the outbreak and response evolve. At present it covers the cost of deploying field personnel, diagnosis and creating more Ebola treatment centers to meet the needs of treating up to 20,000 infections over the course of the outbreak, said Paul Garwood, a WHO spokesperson.

Within this, the estimated resource requirements for WHO’s coordination and crisis management work is $60 million from now till February 2015, said Garwood. “WHO has firm pledges of $4 million,” he said, but the global agency “currently faces a gap of nearly $56 million.”

At least 750 additional international staff and 12,000 more national health workers are presently required for effective action against the spiraling epidemic, as per the WHO. Latest estimates suggest that at least 980 Ebola treatment center beds are required – 760 in Monrovia alone.

In the last few weeks, fatality rate of the Ebola outbreak has risen to 53 percent. While more than 100 new cases were reported in Guinea in the past week, Liberia remains the most affected country, where more than 200 cases have been reported every week for the past three weeks. Incidents have also risen in Sierra Leone in the last couple of weeks, with more than 300 new patients registered there.

Huge toll on health workers

While the disease spreads rapidly and resources are limited, health workers have been the most affected by this Ebola outbreak. Till August 25, the disease has affected around 240 health workers, killing exactly half of them. These include prominent doctors in Sierra Leone and Liberia.

Lack of personal protective equipment has been one reason for this huge toll, and equally worrying is the few doctors available for treating patients. The three hardest-hit countries have only one or two doctors per 100,000 people as per WHO estimates, and the continuous spread of the disease among health workers has made it even harder to recruit medical support for the affected region, said WHO.

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