Ebola: Hope rises for vaccine

Vaccinated monkeys have developed “long-term” immunity to the Ebola virus, raising a prospect of successful human trials, say scientists.

The experiments by the United States (U.S.) National Institutes of Health showed immunity could last at least 10 months, according to a report by the British Broadcasting Corporation (BBC).

Human trials of the vaccine started last week in the U.S. and will extend to the United Kingdom and Africa.

The World Health Organisation (WHO) said more than 2,000 people have died in the outbreak in West Africa.

Several experimental treatments are being considered to help contain the spread of Ebola. This includes a vaccine being developed by the U.S. National Institute of Allergy and Infectious Diseases and pharmaceutical company GlaxoSmithKline.

It uses a genetically modified chimp virus containing components of two species of Ebola – Zaire, which is currently circulating in West Africa, and the common Sudan species.

The viral vaccine does not replicate inside the body, but it is hoped the immune system will react to the Ebola component of the vaccine and develop immunity.

Animal research, on which the decision to begin human trials was based, has now been published in the journal Nature Medicine.

It shows four crab-eating macaques all survived what would have been a fatal dose of Ebola virus five weeks later.

However, only half survived an infection 10 months after immunisation.

Dr Anthony Fauci, the director of the U.S. National Institute of Allergy and Infectious Diseases, told the BBC: “The good part of this vaccine is that at five weeks or earlier you get full protection.

     “The sobering news is the
      durability isn’t great, but if you
      give a boost, a second shot, you
      make it really durable.”

     “We knew this worked in the
      monkey months ago and based
      on this paper we started
      human trials.”

For now this is the best evidence available on how successful such a vaccine would be in people.

The first patient, a 39-year-old woman, was given the vaccine last week as human trials got under way.

There will also be separate trials of the vaccine against just the Zaire Ebola species.

These will take place in the US, the University of Oxford in the UK as well as in Mali and Gambia.

The WHO said safety data would be ready by November 2014 and, if the vaccine proved safe, it would be used in West Africa immediately.

Healthcare workers and other frontline staff would be prioritised for vaccination.

The number of doses currently available is between 400 – if a lot of vaccine is needed for immunity – and 4,000 if smaller amounts are sufficient.

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