NewsWest AfricaThe challenges of finding a vaccine for Ebola

Sat,24Jun2017

Posted on Friday, 30 January 2015 13:15

The challenges of finding a vaccine for Ebola

By Yemisi Akinbobola

Julien Potet, the Policy Advisor on Neglected Tropical Diseases Vaccines with Medecins Sans Frontieres. Photo©ScreenShot/YouTube/Positive Economy ForumJulien Potet, Policy Advisor on Neglected Tropical Diseases Vaccines with Medecins Sans Frontieres, talks about the challenges and advances made thus far in finding a treatment for Ebola.

Question: What research had been done prior to the 2014 Ebola outbreak?

Julien Potet: The virus was isolated as early as 1976 but for decades there wasn't much research, funding or development on it. However, things changed in 2004 when the Ebola virus was recognised as a potential bio-threat in the US and some funding was injected for projects on different vaccines. The recent progress in some products now in development is a direct result of this investment.

countries have limited capabilities to pay for the vaccine

Why is it that the Ebola virus has been around for so long, yet the interest in developing a vaccine has only been in the last 10 years?

The disease was first thought to only affect a limited number of people, mostly in rural areas in Central Africa. We have seen that this is not necessarily the case looking at the current outbreak in West Africa. From the point of view of the pharmaceutical industry and the private investors, the market for Ebola disease was very limited, precisely because the type of people affected had limited capability to pay for such treatments, and the countries have limited capabilities to pay for the vaccine. That is why research and development by private companies has been so limited over the years.

What's the difference between the GSK and NewLink vaccine candidates?

They are both viral vector-based vaccines, which means they use a reconstructed virus that is able to express a critical antigen for Ebola. However, they do not use the same vector. The GSK vaccine uses adenovirus, whereas the NewLink's vaccine uses a virus named "VSV".

Are the vaccines specifically for the Zaire Ebola strain? And does it mean they cannot be used for the Reston and Sudan strains?

Yes, the vaccines are specifically for ZEBOV [the Zaire strain].

So far volunteers tested with the vaccine have been from Western countries? Does a person's race affect reactions to a vaccine?

You are absolutely right. Medical products should be tested across a broad range of the population with different genetic profiles. More importantly, these vaccines may have different efficacy levels, depending on pre-existing immunity of the target population to the vector that is used. In other words, in-patients who are already immune to a specific adenovirus, the adenovirus vector-based vaccine may not work well. That is why GSK researchers use a chimpanzee adenovirus, not a human adenovirus. Pre-existing immunity to chimpanzee adenovirus is expected to be low.

So would testing for immunity be done at some stage?

There have been some studies on pre-existing immunity to these different viruses, but individual testing is not an option in the current circumstances.

How will the distribution be managed ethically?

The vaccines have not been distributed so far because they have not been tested in humans. There is need to differentiate what has been happening in terms of treatment, and what has been happening in the development of vaccines. As far as vaccines are concerned, they are still in pre-clinical stages which means they are being tested in many more models. Some of them now are being tested in healthy volunteers, which is the first step for any type of vaccines before testing in patients.

For Doctors without Borders, what has been the reality for healthcare workers on ground and what issues may be hindering their efforts?

First of all, we have been in last few months calling on other organisations and countries, including military forces, to support the fight against Ebola. We need to increase the number of beds and equipment in the Ebola treatment clinics as this is crucial to stem and control the epidemic.

If a vaccine was to be made available by early 2015, how soon would we be able to stop the outbreak?

This January 2015 the vaccine will not be made available but it will be tested in a limited number of people, because we are trying to accelerate the study as much as we can. In usual times it takes between three to four years at least before a vaccine is tested in healthy volunteers and before it is introduced at country level. We are trying to reduce this time as much as we can.

Is there anything else you would like to add?

Fast tracking the development of an Ebola vaccine is crucial, not just for the current outbreak but also to prevent future outbreaks in West Africa. The Ebola virus disease is probably going to be here for some time but the vaccine, in addition to operational support, is crucial to prevent epidemics in the future.

Yemisi Akinbobola writes for United Nations Africa Renewal Magazine



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