The Quest for a Bird Flu Vaccine Early clinical trials of a vaccine against the bird flu virus -- potentially lethal to humans -- appear to be a success. Will a vaccine be able to stop a pandemic?
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The Quest for a Bird Flu Vaccine

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The Quest for a Bird Flu Vaccine

The Quest for a Bird Flu Vaccine

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There is good news on the war against the bird flu. The initial trials of a vaccine against the avian flu look pretty good. The flu virus of concern: the H5N1 strain that has killed millions of chickens in Asia and now Russia and has crossed the species barrier to infect people. There have been over a hundred confirmed cases, human cases, of bird flu reported to the World Health Organization to date in Indonesia, Thailand, Vietnam and Cambodia, and out of these, 57 people have died--an incredibly high death rate for the flu.

And fears that the virus will mutate, be able to spread easily from person to person are well-founded because, well, there are not a lot of people around who remember the 1918 flu, the Spanish flu, that killed over 40 million people in less than a year, and another global pandemic would be just as devastating, if not more so.

The vaccine has passed its initial testing phase, with more to go, but if and when a vaccine does become available, health officials say that not everyone will be asked to roll up their sleeves. How much more of the vaccine is the federal government going to order after these two million doses that it has already ordered?

Here to talk about it is Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, part of the NIH. He's on the line with us.

Welcome back to the program, Dr. Fauci.

Dr. ANTHONY FAUCI (Director, National Institute of Allergy and Infectious Diseases, National Institutes of Health): Thank you, Ira. Good to be here.

FLATOW: Give us an update on that test. And what does it actually show? There's a lot of confusion around about what that test actually proves.

Dr. FAUCI: Yeah. What it is, is that a virus was isolated from a Vietnamese patient last year with the H5N1 and was used as what we call the seed virus to make a vaccine. And the initial clinical trial, which started in April of 2005, just a few months ago--the initial first stage of the clinical trial was done in healthy young adults, less than 65 years old, to ask two questions: Is it safe? And what is the proper and appropriate dose that would elicit a response that you would predict would be protective if you were, in fact, exposed to the H5N1?

In the first stage of the trial, the preliminary data, as you said, look good in that we have a proof of concept in that, A, it appears to be safe and, B, it induces a response at the higher concentrations of the vaccine that would be predictive that it would protect against H5N1. The sobering news is that the dose is high, and we are, in fact, faced with the same situation that we have been over the last few years and even beyond that--is that the vaccine capacity, the production capacity, the manufacturing capacity, in this country and worldwide is going to have a tough time making enough vaccine for everyone who might need it, were there a pandemic flu.

So the good news is that the proof of concept is there. There's a lot of work to do now to figure out how we can get away with a lower dose by perhaps adding an adjuvant or an immune booster to the vaccine, as well as increasing the vaccine manufacturing capacity.

FLATOW: So this vaccine would not be ready for prime time yet, even if you could produce it.

Dr. FAUCI: We would not. I mean, there's no plans to pre-emptively deploy the vaccine prior to an indication that the virus that's circulating in Asia now has assumed or developed the capability of efficiently and in a sustained manner going from person to person. The mode we are in now is the stockpiling mode. We've stockpiled already approximately two million doses, which will now really turn out to be less because of the higher dose that's needed. And there are plans to order, to manufacture and order, more of them, but none of those plans include immediately deploying the vaccine to anyone until we have an indication that we've reached the trigger point where the virus is spreading.

FLATOW: So you'd wait for it to show that it has mutated, to spread?

Dr. FAUCI: Yeah. We'll wait for it to show that it has assumed or developed the capability of spreading efficiently and in a sustained manner. If it stays the way it is right now, namely smoldering as it is in Asia, with a inefficient transmissibility from chicken to human, and an even less efficient transmission from person to person, with only a rare--one or two cases that have been confirmed, we would not be vaccinating people right now.

FLATOW: Is it surprising to you, in your experience, and other public health officials that the vaccine has not mutated yet?

Dr. FAUCI: You know, it's very unpredictable, Ira, and that's the one thing we keep saying, and it's the truth, that influenza viruses are quite unpredictable. The fact that it is present now in large numbers of chicken flocks in Asia is a bad sign, because the more chickens are infected, the greater possibility the virus has to jump to humans. The more humans that are infected, the greater possibility it has to evolve to more efficiently affect humans. It's evolving slowly in that direction, but it's been months now in Asia in which we've had this, and we have not seen efficient spread or efficient evolution to the capability of spreading. That does not mean that a few mutations down the pike it might be able to do that. We don't know. We really need to be prepared for it, but it's impossible. We often get asked to give a number, what chance of--it is that this will happen: Is it 20, 30, 40 percent? What is it? It's impossible to give that.

FLATOW: So what is the game plan if it is discovered that it has mutated? Do you rush to a place with the vac--how do you use those two million doses here...

Dr. FAUCI: Right.

FLATOW: this country and the other doses around the country?

Dr. FAUCI: Well, that's a very good point. There are two components. Well, there are several, but two important components is--as a global community, the WHO and many nations, including ourselves, are in discussions now about how you can have a concerted response to the point of outbreak. For example, if there is the beginning of an efficient spread from human to human in a particular area, be that Vietnam or China or what have you, there would be the development of stockpiling of drugs, as well as trying to get whatever vaccine is available, deployed there to try and, quote, "nip it in the bud."

As important as getting the material there is the surveillance and transparency about what is happening there. We can't find out about things a month, a month and a half later. We really need to know almost in real time if the virus is, in fact, evolving. So there are global plans to do that.

The national plan is to develop and stockpile as much as you can so that, if it does get to our borders--and we hope that never, ever happens, but if it does, then we have a prioritization of the people who would be vaccinated first with limited supplies. And I can tell you right away, Ira, that there will be limited supplies, because there's not the capacity to make enough vaccine for everyone.

FLATOW: Mm-hmm. And so you would get the first responders, possibly, vaccinated?

Dr. FAUCI: Yes. Yeah, absolutely. The front-line health-care workers and even the people who will be manufacturing and making the vaccine are very high priority for those who should get it, because, A, you want to be able to take care of the sick people, and you also want to be able to continue to crank out the vaccine from the plants. And then after that, you'd go through the usual risk categories that we developed during the period of shortage last year. You might recall that individuals 65 years of age or over who have chronic medical conditions, people with chronic disease like heart disease and diabetes and immunosuppressive diseases, pregnant women and other groups.

FLATOW: Mm-hmm. And would you go to the area where the first outbreak has occurred, or would you spread it around the country? Would you try to concen...

Dr. FAUCI: No, the fir--yeah. No, that's a very good question, Ira, an excellent question. If, in fact, you have a point-source outbreak in the country and it doesn't start off diffusely spread, you would try your best to contain it within the region in which it has begun to spread. Hopefully, it never happens. If it does, it would be to our advantage to be able to do that point-source surrounding of the infections, as it were, with public health measures, vaccine and selective type of treatment. But, however, epidemics don't generally necessarily work that way. You could have a transmission from a connection to an Asian country, where people get off a plane and...

FLATOW: Right.

Dr. FAUCI: ...just disperse themselves throughout the country, and then you have a real problem, which is one of the reasons why public health measures of surveillance and the ability, for example, to isolate and quarantine become an important part of the public health measure.

FLATOW: Do we have those tools in place?

Dr. FAUCI: We do.

FLATOW: Do we have the money to pay for those locally...

Dr. FAUCI: Yeah.

FLATOW: pay for that kind of stuff?

Dr. FAUCI: Well, if not, it will be there. The president, as you probably know, signed an executive order some months ago to extend the quarantine capability to pandemic flu, so the authority to do that type of quarantine and isolation is there.

FLATOW: Mm-hmm. Now we can just come full circle now and talk about the vaccine itself. It's out of its first phase. What comes next--what kind of testing?

Dr. FAUCI: Well, right now, we're going to move--as soon as we get the final data on the young adults who are healthy, less than 65, the next thing is to move into elderly individuals who are greater than 65 years old. That will occur reasonably soon, within the next month or so, certainly as we get into the fall, and hopefully we'll have the data from that cohort group by the end of this year. And then after that we'll move into children in order to determine, again, the safety and the immunogenicity, or does it induce a predictively protective immune response?

Simultaneously with that, we're beginning studies to see if we can do what's called dose-sparing strategies, namely how we can administer this particular vaccine at a lesser dose and still get the same effect. You can do that by how you administer it, into the skin vs. into the muscle or, more importantly, together with a substance which we call an adjuvant, which can greatly amplify the response. Again, those studies with one company are going to begin in October, and with another company are going to begin somewhere in the beginning of 2006.

FLATOW: And--oh.

Dr. FAUCI: So those are the parallel steps that'll be going on.

FLATOW: Is there more than one company that might supply the vaccine?

Dr. FAUCI: Yes. Yes. Right now we have--we're very actively engaged with Sanofi-Pasteur, which is the company from which we got the results that were discussed in the press last week. Chiron is the other company which will begin a very similar clinical trial in October. We're all set to go with them.

FLATOW: Chiron was the company that failed last time, wasn't it? Or...

Dr. FAUCI: Well, it depends what you mean by failing. Chiron was the company that had the unfortunate situation where one of their plants in Liverpool, England, that was making the vaccine that we generally use for seasonal flu--there was a contamination there which prohibited us to get the up to 50 million doses that we thought we were going to get last flu season. But they're up and running now, and they're involved in not only the seasonal flu, but also helping out with trying to make a vaccine against the H5N1.

FLATOW: Can we do both the seasonal and the other vaccine at the same time?

Dr. FAUCI: No. That's a very good point, and that's the strategy that you need to monitor, literally, week by week. There is a window of opportunity between the seasonal flu manufacturing when the plants are available to make a pandemic flu. And we're trying to squeeze however many tens of millions of doses during that period. But then there comes a time soon, you know, as you get into the coming winter, where you have to make a decision...


Dr. FAUCI: ...are you going to go with the seasonal or with the pandemic flu? And we'll make that decision at that time.

FLATOW: Thank you very much, Dr. Anthony Fauci, for being with us.

Dr. FAUCI: You're quite welcome.

FLATOW: We'll be right back after this short break. Stay with us.

I'm Ira Flatow. This is TALK OF THE NATION/SCIENCE FRIDAY from NPR News.

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