RAY SUAREZ: Now more about the health measures and questions surrounding this story, and that comes from Dr. Anne Schuchat. She's director of the CDC's National Center of Immunization and Respiratory Diseases.
Dr. Schuchat, in just the past hour or so, the World Health Organization has raised the level of alarm on this flu outbreak from three to four. What does that mean?
DR. ANNE SCHUCHAT, U.S. Centers for Disease Control: You know, technically what that means is that there is agreement among scientific experts that there's sustained human-to-human transmission of this virus, but it's really less important here in the United States, something that's more important for countries that haven't yet seen a case of this new swine flu virus.
Here in the United States, we're already taking the types of aggressive actions that you would do when you're concerned about a new virus and its potential for spread.
RAY SUAREZ: What's the best information you have this evening on the number of confirmed cases in the United States?
DR. ANNE SCHUCHAT: We're saying that there are 40 laboratory-confirmed cases here in the United States. We're really not focusing that much on the numbers, and we're updating them once a day. They'll be on our Web site every day updated.
What's really important to know is that there are cases in a number of states, that so far of the 40 cases we've had one has required hospitalization, and all have fully recovered.
But we really need to keep our eyes out for a change in the spectrum of disease, perhaps more serious cases. I do expect there to be more cases and the spectrum of illness to change.
RAY SUAREZ: Well, you've said human-to-human contact is important. Are any of these American cases ones that were contracted here in the United States and don't involve people who've traveled recently to Mexico?
DR. ANNE SCHUCHAT: You know, we have information about an outbreak in a school in New York City and some other similar school situations. And the story there is that most people didn't travel to Mexico. The thought is that they got the infection from each other.
So we do think that we have person-to-person spread here in the U.S., and that's why we're taking steps to make sure people know what they can do to reduce the spread of respiratory infections, whether they're swine influenza or other respiratory viruses, things like washing your hands, covering your cough or sneeze, staying home when you're sick, not going to school or work, not getting on airplane or a bus, really staying away from crowds, if you're sick, trying to decrease the chances that you'll spread your respiratory infection to somebody else, whether it's this new swine flu respiratory infection or just a regular one.
RAY SUAREZ: When you've got a known cluster of cases, as you have in California, in Kansas, in New York City, how does an epidemiologist work to corral it, make sure it doesn't get out of that small cluster?
DR. ANNE SCHUCHAT: You know, there are several steps that we take. And one of the important steps at this point is to understand what's going on. That's our critical part of the investigation, to understand how the virus is spreading, so that we can identify the most effective intervention tools.
There are some classic approaches that we take: isolating people who are sick, so that they don't spread to other people and keeping their contacts away from a lot of other people. We also heighten attention at surveillance to try to detect cases promptly so that we can isolate them.
You know, when we had the SARS outbreak several years ago, we didn't have any drugs that worked against that new virus. We didn't have vaccines. But the simple measures of aggressive surveillance, isolation, and, really, social distancing were able to put that virus back in the box, really.
RAY SUAREZ: You mentioned that only one of the American cases has had to be hospitalized. And a similar pattern seems to be emerging in New Zealand, in Canada, in Spain, and other places where this strain has popped up. Why does the disease seem to be milder outside Mexico than in it, where many people have died?
DR. ANNE SCHUCHAT: I think it's premature for us to conclude that the virus is milder in our country. And it's an important question that we have, whether we will see more severe cases.
We don't at this point in the U.S. know of as much disease as they apparently have in Mexico, and so we're looking intensively. It would be wonderful if we don't end up having the kinds of hospitalizations and very severe outcomes that we've seen in Mexico reports, but I think we have to be on the lookout.
And that's why the government and the public health system have been taking such active steps to really make sure that we do all we can to reduce the health impact of this virus and to slow the spread of the infection.
RAY SUAREZ: It's early days yet, but have we had a chance to determine whether the American cases are the same strain as the ones in Mexico? In fact, whether all the people who've died in Mexico even have died of the flu?
DR. ANNE SCHUCHAT: Both of those issues are being looked into. It's really remarkable to me how much has been done with the virus isolates. We've relatively quickly been able to do quite a bit of study of them.
And so far what we've found is that the virus characteristics from Mexico are the same as what we're seeing in the U.S. isolates. We haven't tested every single one to the great extent that we did with the initial few, first few, but we so far haven't found important differences. But that's an issue of great interest.
We're also taking intensive steps in partnership with the Mexican authorities and Canada. We're part of a tri-national team in Mexico now to understand what is going on there and, as you say, to find out how many of these severe illnesses that we're hearing about could actually be attributed to this new swine flu virus.
There are several causes of severe respiratory illness in people, many different viruses and bacteria. And we don't know yet for sure whether most, some, or a small amount of the severe illness we're hearing reports of in Mexico is caused by this particular new virus.
RAY SUAREZ: Doctor, how does a new strain of a flu get started in the first place?
DR. ANNE SCHUCHAT: Influenza viruses are in people and in animals, and they're constantly changing. They can recombine or re-assort and evolve over time and sometimes acquire these new characteristics, the ability for an animal virus to become able to infect humans, the ability of a human virus to be able to affect animals. There's quite a bit of change in the virus that's possible.
And so we've been working over the past few years to really strengthen the capacity here in the U.S. to detect unusual strains of influenza as part of our pandemic preparedness efforts.
We had developed new diagnostic tests and trained the state and local public health laboratories to be able to use these new tests and to find that bird flu strain that we were talking about a few years ago, the H5N1 strain, but also to find strains that couldn't be typed at all.
And it's through that effort that we first became aware of the swine influenza virus out in San Diego, through this effort to aggressively work up atypical influenza viruses.
RAY SUAREZ: Just a short time ago, the head of the World Health Organization talked about racing to prepare a vaccine for this strain. Just before you appeared on the program, the secretary of homeland security talked about distributing Tamiflu. Until there is a vaccine, who should take Tamiflu prophylactically?
DR. ANNE SCHUCHAT: CDC is updating our Web site regularly and has issued interim guidance about antiviral use, as well as diagnostic testing and lots of other great information.
At this point, we're recommending antiviral use for treatment of the swine influenza virus. There is some consideration for preventive use of the antiviral drugs for household contacts of someone with the swine influenza virus, if those household contact members have underlining risk factors for worse outcomes, you know, the elderly or other underling disease.
There are additional guidance that we've developed in conjunction with a number of experts in infectious disease and virology. So those are interim guidance.
And it's important for viewers to know that influenza is unpredictable, and a new swine flu virus is also unpredictable. And all of our recommendations or guidance documents are really interim. We are committed to learn as we go and to update guidance when we find new information.
An important factor about the Tamiflu is that so far we have tested the viruses and they're sensitive to Tamiflu, which is a good thing. So we do think that Tamiflu would be effective for treatment, and we're glad that we have a lot of it right now.
RAY SUAREZ: Dr. Anne Schuchat of the Centers for Disease Control, thanks for joining us.
DR. ANNE SCHUCHAT: My pleasure.