RAY SUAREZ: Throughout the past week, there have been new alarms and new calls to action about a possible flu pandemic. It all stems from a deadly flu strain passed from birds to humans. The strain, known as H5-N1, and more commonly referred to as Avian Flu, turned up again this winter in Southeast Asia, leading to new cases in Vietnam, Thailand and Cambodia.

So far, there have been 97 recorded human cases and 53 deaths since 2004. While those numbers are not so large now, the World Health Organization reports the virus is continuing to mutate in ways that makes it increasingly infectious to people. And today the scientific journal Nature devoted much of its issue to the subject, warning of a potential pandemic that could kill millions if preparations did not improve.

For a closer look at all of this, I'm joined by Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases. He wrote a commentary in today's issue of Nature. And Laurie Garrett -- she runs the global health program at the Council on Foreign Relations.

Dr. Fauci, one of the core issues, I guess, for understanding this disease is what we know about how it gets passed from birds to humans and whether humans pass it to other humans. Do we have a good handle on that yet?

DR. ANTHONY FAUCI: We know it has already jumped from birds to humans, and that's the thing that is the first part of the real concern, because this is a virus, the H5-N1, which the human society has had no prior experience with. So there's no residual or baseline immunity. It's a brand-new thing for them, which means that the protection that we generally get from year to year.

Like right now this season the regular seasonal flu was an H3-N2, was a little bit different than last year's H3-N2, a little different than the previous year, but we have cumulative experience. The H5-N1 is a major shift. As we call it, those little changes are drifts. And what happens is that you get chickens infected and this virus has adapted itself to jump from chickens to humans in Asia.

The biggest focus right now is in Vietnam. When it gets efficiency in going from human to human, and viruses tend to evolve, to go toward that which will help propagate it -- there have been now 97 infections, as you mentioned, and 53 deaths. So it's still inefficient in going from bird to human. There have been two well-documented cases of human-to-human.

So by mutation or adapting itself, it very likely could get better and better in its efficiency in going from human to human. Once that happens, Ray, then you have a really bad situation, because if it spreads widely, you have people who have no prior experience, so they don't have any baseline immunity to respond rapidly.

The other important point is that this is a very highly lethal virus; it's killed 53 out of the 97 documented cases. It's unlike what we see in the regular flu, which is less than 1 percent. So the potential for this being a really serious problem is there, and nothing that's happening is telling us that it's going in the other direction. It keeps going in the direction that is making us quite anxious. It's increasing its host range, and it's changing ways, there are more clusters that are not explainable. So we have a very serious situation here.

RAY SUAREZ: Laurie Garrett, what's the best scientific opinion if you survey about how much of the threat Avian Flu poses worldwide and Asia in particular?

LAURIE GARRETT: Well, certainly in the public health community and in the community of virologists that know a lot about flu, concern is very, very high. I was just at the World Health Assembly, which is the governing body of the World Health Organization, for a week of meetings in Geneva, and everybody was talking about flu.

It's the number-one concern on the minds of most global health experts right now. And there are a number of reasons why this year we're more worried than we have been in my lifetime. We've seen this H5-N1 strain, which is unlike any strain, as Dr. Fauci was explaining, human beings have ever seen before. So you don't have antibodies to it; I don't have antibodies to it.

As far as we know, nobody has antibodies to it. We've seen this thing go through a series of mutational changes over the last two, three years, and just very recently it's been confirmed -- actually just today -- confirmed by the Indonesian government that they've identified an outbreak of it in pigs in Indonesia.

This is very worrying, because what this means is that the virus may have found a way to infect another species of mammals, big difference from infecting birds, Ray. If it starts infecting pigs and other mammals, then it's a quick leap to whatever genetic change is necessary for this virus to evolve into the kind of flu that is incredibly contagious from person to person.

And it's important to understand, when we talk about contagious viruses -- and I know lots of people have heard of the so-called scary ones like Ebola and Marburg -- these are actually really hard to get compared to flu. This influenza virus can sit on a doorknob for six days and still be infectious to somebody who comes along six days later; someone rubs their hand on that doorknob and, as we all do, happens to infect themselves.

It is so infectious, so contagious that at the World Health Organization meetings I was at, people are really tearing their hair out trying to figure out how we could control it, how could can stop it from spreading all over the world. Our host of classic ways of dealing with public health problems of various kinds is very, very limited in this case.

RAY SUAREZ: Well, is there, Dr. Fauci, a public health approach to seal up something like a flu in a geographical area? Laurie Garrett mentioned Ebola and Marburg. Those haven't spread worldwide. Is there a way with a flu like this to just cordon it off?

DR. ANTHONY FAUCI: Yes and no. Because, as Laurie said very accurately, it spreads so rapidly that it isn't the kind of thing that's easily containable. But, having said that, good public health measures of identification, reporting accurately and in a transparent way, when you get the opportunity to isolate people, and the president himself signed a quarantine, an executive order to be able to quarantine and add pandemic flu to the list of quarantinable diseases.

But it's a combination of public health measures, coordination among nations, vaccine and drugs. Now, the problem that we're facing, we have assumed that this is serious enough that we are already in trials of an H5-N1 vaccine that we started in April. We've already completed the first two stages of it in healthy adults. We're going to analyze the data for safety and what's the right dose because, unlike the regular flu vaccine, where you know you can give one dose and get a good immunity.

Since we haven't seen this before, it is likely that we'll have to use a higher dose and/or two vaccinations. When this data comes, we'll move to the elderly and then we'll go to children. The problem is that the vaccine-manufacturing capacity of the world is only anywhere between 300 million and 450 million. There are six billion people in the world.

So we have a problem with capacity that even if we don't -- and it is likely we don't -- even though we're very concerned, Laurie and I and many others, that we'll have a problem soon, if we don't have it this year, this isn't something that's going to just disappear. This is here to stay. We will have a pandemic sometime. It may be this year, next year, the year later.

And what we're concerned about is that we've got to build up the capacity to have countermeasures in the form of vaccines and therapeutics as opposed to saying, "We got through this year; let's just go back to square one." We have a vaccine production industry that is in fact very, very fragile, and we actually discussed this on this show not too long ago when we were dealing with the shortages of flu vaccine from the previous winter.

RAY SUAREZ: So, Laurie Garrett, does the world end up on the horns of a paradox again where those countries that are most able to provide vaccine to their people are actually the places least in threat of having an Avian Flu outbreak, while the places that are most threatened are the least able to respond?

LAURIE GARRETT: It's worse than that, Ray. I mean, the problem is when you sit down with a global organization like WHO, 192 member countries, everybody passes a resolution saying, "We're very worried about pandemic flu; we're terribly concerned this could be the year that we see a flu that could take millions and millions of lives worldwide."

Well, then you pass a series of resolutions. You must stockpile drugs, you must try to make vaccine; you should have a national plan of action. All those are great to talk about in the context of a wealthy country like the United States or any of the European countries.

But what do you say to Chad? What do you say to Tanzania? What do you say to Vietnam? Poor countries can't muster up the kinds of plans we're talking about. And worse yet, in 1918, we did not have hundreds of millions of people with immune deficiency in the world -- immune deficiency either because they were elderly, cancer patients, or probably most significant because they had HIV disease and did not have access to drugs to treat the HIV disease.

We basically have the equivalent of a hillside of dry brush, when you think about Africa right now and the amount of HIV there, where you're lighting a match at one end and just watching that fire burn up that hill. That's what pandemic flu might be when it hits Africa.

RAY SUAREZ: Let me get a quick response on that point from Dr. Fauci. Are we getting ready enough in advance to help stave off some of the worst effects?

DR. ANTHONY FAUCI: There's no doubt this is the number-one priority of secretary Levitt in the Department of Health and Human Services rights now. We meet virtually daily about this. I mentioned the vaccine trial. We've stockpiled Tamiflu, which is the drug that this particular microbe is sensitive to. We don't have enough. It's 2.3 million treatment courses.

We need a lot more, and we'll get a lot more. So we're being very proactive about it. Again, being proactive is what we need to do, but this is such an enormous problem involving the entire global community, as Laurie mentioned, that we alone, even though we are far ahead of others in this regard, we alone are not going to solve the problem. It's got to be global collaboration.

RAY SUAREZ: Anthony Fauci, Laurie Garrett, thank you both.