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As H1N1 Flu Spreads, Researchers Rush to Analyze Strain

May 1, 2009 at 12:00 AM EDT
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After a report from Betty Ann Bowser on the CDC's latest efforts to stop the spread of the H1N1 flu, Margaret Warner talks to health experts about what's being done to better understand how the virus works and why it has proven deadly in some cases.

JUDY WOODRUFF: Much of the surveillance and tracking of this outbreak is being managed by the Centers for Disease Control and Prevention in Atlanta. Our health correspondent, Betty Ann Bowser, spent the day there to see how it’s being done.

BETTY ANN BOWSER: This is the CDC’s Emergency Operations Center. It’s a frenetic sea of activity for tracking cases of swine flu worldwide, a 24-hour-a-day hub.

Toby Crafton manages the center.

TOBY CRAFTON, U.S. Centers for Disease Control: These are folks from all across the agency representing different functions that we need to — to conduct a response.

BETTY ANN BOWSER: What other agencies are represented in this room?

TOBY CRAFTON: There are several other agencies within the federal government that we represent here. DOD is one. We have a Department of Defense…

BETTY ANN BOWSER: Defense Department?

TOBY CRAFTON: That’s right, Defense Department liaison.

BETTY ANN BOWSER: Why are they here?

TOBY CRAFTON: Because they’ve got a lot of people around the world that could potentially be exposed. And for national security, their health is important.

BETTY ANN BOWSER: What happens at this bank of computers and all these folks along here?

TOBY CRAFTON: Our operation center is open 24 hours a day, 7 days a week.


TOBY CRAFTON: Any time, 24/7, 365 days a year. And so these folks are here all the time. And when a call comes in from a state health department, sometimes we get calls from physicians, even citizens, they call — our number is posted on the Web site.

BETTY ANN BOWSER: What kind of questions are coming in? Or what kind of calls are you getting? Give me an example of something that might be coming in from Europe, let’s say, or from some place, let’s say, Denver, Colorado.

TOBY CRAFTON: Well, they may have a suspect case, and they want to know what they need to do. They may ask clinical questions, which we don’t answer here. We pass those on to the clinical teams that we have standing behind you here.

But it could be a laboratory wanting to know if they — what they should be doing, how they should ship specimens to CDC, where they should send them, and that sort of thing.

BETTY ANN BOWSER: This is where the calls come in first, to a duty officer like Gordon May.

GORDON MAY, CDC Duty Officer: We would put them in touch with the SME, the subject matter expert.

BETTY ANN BOWSER: And if it’s a local or state health official who thinks they may have another case of the H1N1 virus, he sends the call to the right desk. Phyllis Nichols is part of the epidemiology surveillance team.

PHYLLIS NICHOLS, CDC: We get international e-mails. We get e-mails from states, from laboratories, from consumers, from our federal partners.

BETTY ANN BOWSER: What kind of things do they tell you?

PHYLLIS NICHOLS: There’s anywhere from questions people have about things that they’ve read on our Web site that they might have additional questions with that we can refer to our epidemiologist downstairs to questions about updates on case counts, case reports, rumors.

BETTY ANN BOWSER: Sean Griffiths is part of the same group. He’s from the federal Department of Health and Human Services on-site team assigned to the CDC. The team is also like a group of firemen trying to throw cold water on rumors.

SEAN GRIFFITHS, U.S. Department of Health and Human Services: Because, you know, everybody is experiencing a great deal of stress — we’ve been working for, you know, days — and so both in the field and here, folks are, you know, under a lot of pressure. And so sometimes just having a voice, a contact, somebody to speak to and just hear them out, sometimes that’s part of our job.

The virus's history

BETTY ANN BOWSER: But this is where information is generated to put those rumors to rest, in CDC's influenza lab, where virus samples from all over the world are tested for the H1N1 virus.

Dr. Michael Shaw is a molecular biologist who's in charge of the lab.

What about reports today that say that this has never been found in swine?

MICHAEL SHAW, CDC: This particular combination of genes in the virus has never been seen anywhere, in any animal, or in any people before this outbreak.

BETTY ANN BOWSER: Then how can it be called swine flu?

MICHAEL SHAW: That is mainly for historic reasons. Because if you look at its genes, you can trace it back to a 1930 isolate that came from a pig. When you start calling something swine flu in 1930, it's sort of hard to break the habit by now, which is what we're trying to do. But the fact is, this virus has only been seen in people so far.

BETTY ANN BOWSER: We asked why the virus seems to be killing young people in disproportionate numbers.

MICHAEL SHAW: It may be that people above a certain age might have some immunity because of something, some flu virus they had early in life. That's one of the things we're looking at, where we're seeing if there is an age difference in antibody response to this virus.

Prior to 1957, there was also an H1N1 virus circulating. That may be the cutoff. It may be people born before 1957 having been exposed to a similar virus might have a better immune response to it. We don't know. We're looking at that.

There's only one class of drugs that works with this virus right now, Tamiflu and related drugs. So we need to know as soon as possible if any signs of resistance are showing up. That's what these people are doing. They're checking to make sure that the viruses are still sensitive, and everything we've seen so far is still sensitive to the drug.

BETTY ANN BOWSER: The Tamiflu works?

MICHAEL SHAW: Right, yes. But if that changes, we need to know about it as quickly as possible, which is why these people are -- everybody here is working 24 hours a day on this. Nobody is stopping.

BETTY ANN BOWSER: Right now, CDC officials are making virus samples available to drug manufacturers, but no decision has been made about when to start producing vaccine for mass consumption.

Explanations for virus's variation

MARGARET WARNER: As researchers work around the clock, they're trying to get a grip on a number of medical and scientific mysteries about this particular flu strain, its infection rate, and its virulency.

We explore some of that now with Dr. William Schaffner, chairman of the Department of Preventive Medicine at the Vanderbilt University School of Medicine. He's an expert on infectious diseases.

And Laurie Garrett, a senior fellow for global health at the Council on Foreign Relations, she's working on a book about the global impact of infectious disease.

Welcome to you both.

Dr. Schaffner, I know we don't know the answer to this question, but what are some of the possible explanations for the fact that so far the only people who have died have been in Mexico or that little boy who had just arrived in the states from Mexico?

DR. WILLIAM SCHAFFNER, Vanderbilt University School of Medicine: Well, there are a number of different explanations, Margaret. The first is a standard public health investigation answer.

The Mexican authorities probably focused on the most severely ill people who are in hospitals and who were dying. And it may well be that the subsequent investigation will show us that many, many people got sick, but only a relatively smaller proportion needed to be hospitalized and died.

And then, when you do that calculation, the fatality rate then may approach what we normally see in an influenza outbreak, so that's the first explanation.

There are a couple of others. Another is perhaps access to medical care is different in Mexico than it is in the United States or perhaps there were co-infections with other viruses that were going on at the same time.

Perhaps the virus actually was different in Mexico and the United States. Perhaps it mutated again. But the laboratorians have told us that's not likely to be an explanation, so we're going to wait for the rest of that public health investigation to be completed in Mexico to see if we can sort that out.

How a virus mutates

MARGARET WARNER: And, Laurie Garrett, how important is it to sort that out?

LAURIE GARRETT, Council on Foreign Relations: Oh, I think it's very important to have that sorted out, because here we are at pandemic level five. There's only one other World Health Organization level to go to, number six. These threat levels are based on the geographic spread of the virus, not on its severity, not on how dangerous it is.

And unless we know the answer to really how dangerous it is, which basically means to what's going on in Mexico, all these threat-level rises simply create a kind of level of anxiety in the world without it being directly correlated with just how serious the disease may be.

MARGARET WARNER: So, Dr. Schaffner, going to the severity question -- now, we've heard some scientists opining that maybe this is going to be milder than thought. Others are saying, "Not so fast." How does a flu virus mutate? In other words, can it mutate in either direction, more dangerous or less so?

DR. WILLIAM SCHAFFNER: Well, yes, it can. It turns out that the influenza virus has in its genetic elements a capacity to mutate very readily, in contrast, for example, to the measles virus, which has been the same for eons. It doesn't change.

As we all know, the flu virus changes from season to season, and it does so either internally -- it can just mutate its own genetic material -- or it can combine with other viruses in the same animal, for example, in a pig.

The pig can be infected with a swine influenza virus, and then a human influenza virus, and then they can exchange their genetic material and create a new virus.

This new virus can adapt itself to humans and become more transmissible and more virulent or its virulence could fall off, all because the influenza genetics is very, as we say, plastic.

LAURIE GARRETT: I think this is an important point, Margaret. Let me take it one step further, if I may.

I think what's going to happen, if I can go out on a limb here and do a little forecast, is that we're approaching warm weather, even hot weather in the Northern Hemisphere. The virus is going to now move to the Southern Hemisphere.

As it moves around the Southern Hemisphere, it will, as it always does -- all flus do -- make some slight changes because of this sloppy reproduction process that you were just hearing described.

And the result may be that what we really need to be thinking about is what's going to come back our way come late September, early October. What will this virus look like after it's made its way around the world and managed to go through not just other humans, but perhaps other animal and bird species in the Southern Hemisphere?

MARGARET WARNER: And, Laurie Garrett, that's what happened with the 1918 flu, isn't it, that the first wave, actually in the spring, I think, was fairly mild, but when it came back in the winter, it was with a vengeance, that's when all the people died?

LAURIE GARRETT: That's absolutely true. The first wave was -- I wouldn't say mild, but moderate enough that the medical command for the British military decided there was nothing to worry about. The troops could stay hunkered down in the trenches in World War I in Europe, not a problem.

But then it passed through the United States and went through Kansas, where we had the cavalry, which in those days was bivouacked with their horses, and through a few other positions in the United States, and all of a sudden we had a super-killer virus on our hands.

New strain is concerning

MARGARET WARNER: So, Dr. Schaffner, is the fact that this flu combines pig, bird, and human flus, flu strains -- I'm probably not using the exact terminology there -- does that make it more dangerous?

DR. WILLIAM SCHAFFNER: Well, it makes it novel. And because it's novel, it's new to us. And so our previously accumulated protection against influenza probably doesn't work very well, at least that's the current assumption.

And that gives the virus, if it can be transmitted from human to human readily -- and we are seeing transmission -- the possibility of being transmitted around the world, just as Laurie says, and then it could take off. And in effect, it has a home in each one of us, each human being on the planet. And that's a pandemic.

MARGARET WARNER: And so, Laurie Garrett, is that why there's such alarm and reaction to this particular flu strain, even though, as we've now learned, 36,000 Americans die every single year from seasonal flu?

LAURIE GARRETT: The alarm around this particular strain has a couple of roots. First is, it's new. As you say, it's new, it's novel. And new is always cause for some amount of concern.

The second is, it does appear to have just recently jumped from one species, pigs, to another, humans. And very commonly, in the whole world of viruses, not just influenzas, when they first make the jump from one species to another is when they're really hot viruses, dangerous viruses.

That certainly was the case with SARS, which had just made the jump from bats to civets, civets to humans. So we always worry when we see a recent jump.

But the other piece of it is this -- that what we just went through over the last two weeks, what it looked like in Mexico as it was unfolding, which, as I totally agree may have been skewed by the initial perceptions of the patient burden in hospitals, particularly in acute care in Mexico City. Nevertheless, that certainly looked like the beginning of a really dangerous epidemic.

And I think one other point that gets lost often in the shuffle in these discussions is, Mexico has made spectacular sacrifices, sacrifices not just for the people of Mexico, but for the whole world.

What they have done, by shutting down most of their economy, all of their schools, most public congregations of all kinds, and having the entire population walking around Mexico City with masks on is greatly reduced the rate of transmission of this virus.

And it's very possible -- and this is something that it's going to take time to sort out -- but it's certainly hypothetically possible that, in the very beginning, this was a hotter virus, a more virulent virus, and all this drop in human congregation has lowered the transmission rate on the virus, and therefore now it appears as if the epidemic is waning in Mexico.

Of course, the real test is going to be what happens on May 6th, when the schools reopen and people come back to work, after the Cinco de Mayo holiday. What happens? Does the virus resurge in Mexico? Or has all of this sacrifice on the part of the Mexican government and economy done the job?

MARGARET WARNER: So, obviously, a lot more to come on unraveling these mysteries. Laurie Garrett and Dr. Schaffner, thank you both.