How long-lasting is promising Ebola vaccine protection?

A clinical trial in Guinea found that an experimental vaccine was 75 to 100 percent effective in blocking new infections of the Ebola virus. Hari Sreenivasan speaks to Dr. Anthony Fauci of the National Institutes of Health about the vaccine.

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    Now a potentially exciting development in the search for an Ebola vaccine, and to Hari Sreenivasan.


    Results of a clinical trial conducted in the West African country of Guinea and published today in the medical journal "Lancet" found an experimental vaccine was 75 percent to 100 percent effective in blocking new infections of the Ebola virus.

    The trial involved more than 7,000 people, over 3,500 of whom were vaccinated. Guinea is one of three West African countries that marked the epicenter of the 2014 Ebola outbreak that killed more than 10,000 people.

    For more on efforts to create a vaccine and on this trial, I am joined by Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.

    So, you have got — there are several different companies and people working on vaccines, including a member of your team, but today we hear words like game-changer, you know, these are significant results. Why was this so important?

    DR. ANTHONY FAUCI, National Institutes of Health: Well, it's significant because of the outcome of the trial. It showed rather impressive results.

    Now, it was done under very difficult circumstances, so that's really very important. It was done right during the intensity of the outbreak itself. And the data that have been released today show that the results are really quite favorable. There is still a lot of work to be done to determine, in fact, if this protection against Ebola is durable, mainly that it can last for several months, because we certainly would like to have this available for future outbreaks.

    And, inevitably, there will be future outbreaks of Ebola. So this is an important step in our armamentarium of preventing Ebola infection, in addition to the public health measures that you do to prevent infection.


    But what did they do? How did they figure out that this is effective?


    Well, it was a very interesting design to the study.

    It's called a ring vaccination study, ring meaning you create a ring around an index case of when someone gets infected, and you vaccinate the contacts of that person and the contacts of the contacts. But the thing about the ring study is that it was randomized, so when they identified a case of Ebola, they had two rings, one in which got vaccinated immediately, and one which got vaccinated 21 days afterward.

    And then they compared the number of infections in those who were vaccinated immediately vs. those who had a delay of 21 days, and the results were rather impressive, because the number of Ebola infections in the people who were vaccinated immediately was zero, and the number of infections for those who had vaccination on a delayed basis was 17.

    Now, relatively speaking, this is an interim analysis of results, but it's still rather impressive. Now we're going to have to look at the details of the data to really delve into what it means. But having said that, it's important that the results came out this way.


    This is — you alluded to this earlier. This is in the middle of an epidemic. This isn't our kind of definition of a gold standard of a clinical trial, where you give some people medicine and some people a placebo, because I would imagine it's almost unethical to not give someone a medication when you see people dying within days of having the virus.


    Well, I wouldn't say it's unethical. But it's difficult to do in situations like that.

    But if you don't know what works, and you do a controlled trial, then you get informed consent about how you're going to do the trial, and then it really is quite ethical. So — but I think that this design was an interesting, novel design. It's fashioned after the design of how we approached smallpox and the elimination of smallpox.

    It was a creative design that was done under difficult circumstances.


    When people think of vaccines, they also think of things that actually have the virus in it. Did this vaccine have Ebola in it?


    No, it didn't. It had a protein of Ebola.

    So let me explain what it is. A virus was used called vesicular stomatitis virus, which is a virus that infects animals. It rarely infects humans. And what the virus was is, you took one gene of Ebola and inserted it into this other virus, and then injected this other virus into the vaccine recipients.

    Once it got in them, it started making the Ebola protein, so none of the individuals got the Ebola virus itself. They got the protein of Ebola that was given to them through this vector or this carrier virus.


    All right, Dr. Anthony Fauci from the National Institutes of Health, thanks so much for joining us.


    Good to be with you.

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