JUDY WOODRUFF: First, the flu story. The illness continued its spread, as the number of U.S. cases passed 100, and more schools closed. Ray Suarez begins our report.
RAY SUAREZ: With at least 16 U.S. states now reporting confirmed flu cases, some localities are taking forceful steps to prevent the virus' potential spread.
Fort Worth, Texas, has closed its entire school system, sending home more than 80,000 students.
DR. SANDRA PARKER, director, Health Department, Tarrant County, Texas: It is the recommendation of Tarrant County public health that the Fort Worth ISD close the district schools for the duration through May 8th and cancel all school-related activities.
RAY SUAREZ: All told, more than 170,000 students in 11 states are being kept from school for as much as a week.
In Atlanta, Dr. Richard Besser of the Centers for Disease Control and Prevention said his agency was acting as if a pandemic were imminent and that federal, state and local efforts are warranted, even in the absence of widespread transmission.
DR. RICHARD BESSER, acting director, Centers for Disease Control: We continue to be very aggressive in our approach, and we're going to continue to do that until the situation tells us that we no longer need to do so.
There's no one action that's going to stop this. There's no silver bullet. But all of the efforts -- the efforts of governments, the efforts of communities, the efforts of individuals -- will help to reduce the impact on people's health.
RAY SUAREZ: The agency is dispensing antiviral medication to nine states as part of its efforts to combat the virus.
The White House press secretary said this afternoon that the H1N1 virus, the technical name of the disease strain, may have affected a member of the president's recent delegation to Mexico and three of the advance staffer's family members.
ROBERT GIBBS, White House press secretary: Further testing is being done by the Centers for Disease Control and Prevention to determine the nature of the outcome. The original patient tested negative, likely because so much time had elapsed since the onset of his own symptoms that they would not show up in the test.
As I said, all four individuals experienced only mild symptoms, and all four have recovered. This person has been cleared to go back to work by doctors and is back working today.
RAY SUAREZ: Elsewhere in Washington this morning, Vice President Biden went significantly beyond previous government travel advisories when answering a question about how he's advising his own family.
U.S. VICE PRESIDENT JOSEPH BIDEN: I wouldn't go anywhere in confined places now. It's not that it's going to Mexico. It's you're in a confined aircraft. When one person sneezes, it goes all the way through the aircraft. That's me. I would not be, at this point, if they had another way of transportation, suggesting they ride the subway.
RAY SUAREZ: The vice president's office quickly tried to clarify the statement, suggesting he was referring only to preventive measures if people are sick.
But his comments led to several questions at a House hearing on the flu with senior government health officials.
REP. ANTHONY WEINER, D-N.Y.: I think you'll forgive our constituents for being a little whip-sawed by the news and images that they get, and I represent the district that has half of all of the confirmed cases in the country.
RAY SUAREZ: New York Democrat Anthony Weiner's district includes the prep school where many of the U.S. cases have been found.
REP. ANTHONY WEINER: Can you just say with clarity about subways, "It is safe to get on a subway. We would encourage you to get on a subway. And if there was a subway to Atlanta, you'd take it"?
DR. ANNE SCHUCHAT, Centers for Disease Control and Prevention: The only people we're saying should avoid, you know, crowded circumstances or airplanes, for instance, are people with fever and respiratory symptoms. We also think it's important for local authorities to be giving the guidance for the community.
But we do not have recommendations to stay away from those transport methods if you don't have respiratory symptoms. And I'm looking forward to getting on an airplane later today to go back to Atlanta.
RAY SUAREZ: At the epidemic's ground zero in Mexico, the health secretary said the number of cases seems to be stabilizing.
Nevertheless, President Felipe Calderon last night urged all Mexicans to stay home from May 1st to May 5th to stem the spread of the virus during the run-up to next week's Cinco de Mayo national holiday.
But he also made a plea for normalcy after the holiday break. Tourists aren't coming; beaches are empty; day-to-day domestic commerce is stalled. Mexico's economy has taken a short-term beating because of the outbreak.
FELIPE CALDERON, President of Mexico (through translator): I want to emphasize that economic and commercial activity continues practically as normal, beyond these days off coming up from the 1st to the 5th. Supply is guaranteed and will continue flowing normally during these days.
There is enough medicine for all the cases registered thus far and for another million, if they were to come up. There is space in hospitals to treat those who would become infected with the virus.
RAY SUAREZ: But officials of the World Health Organization said the flu could return in Mexico as quickly as it seems to have stabilized.
Last night, the agency raised its flu alert level to phase five, out of six, indicating an imminent global pandemic.
Dr. Keiji Fukuda heads the group's global influenza program.
DR. KEIJI FUKUDA, World Health Organization: In terms of the global epidemiologic situation, I think it's fair to say that the situation continues to evolve. We see some countries reporting new cases. We also see that some countries in which infection has been going on reporting continued cases in their countries, and I think Mexico is a good example.
RAY SUAREZ: Fukuda said the WHO was focusing on parts of the globe now moving into fall and winter, traditional flu seasons.
DR. KEIJI FUKUDA: When you have the introduction of a new influenza virus, as we are seeing now, it still usually follows some kind of seasonal activity. So for reasons we don't fully understand, in the winter months of the Northern Hemisphere, we tend to see more activity in the Northern Hemisphere, and in the winter months of the Southern Hemisphere, we tend to see more activity in the Southern Hemisphere.
RAY SUAREZ: The agency has now identified the virus in 13 countries. The WHO also said it will stop referring to the virus as the "swine flu" to avoid misleading people about the dangers posed by pigs. The virus is not directly linked to pigs and cannot be contracted by eating the animal.
JUDY WOODRUFF: Even as government officials are providing daily updates about the situation, there are still many questions regarding public health and personal behavior. Margaret Warner gets some answers.
MARGARET WARNER: In fact, one of those questions was prompted by the vice president's remarks today about avoiding air and rail travel. This afternoon, Transportation Secretary Ray LaHood sought to reassure the public, saying, "All modes of transportation are safe in America."
For more on some the many questions out there, we're joined by Georges Benjamin, executive director of the American Public Health Association. He's a medical doctor.
And Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. He joins us from Minneapolis.
Welcome to you both.
Beginning with you, Dr. Benjamin, what else are states and localities doing now to both identify this new flu in their area and to try to anticipate or mitigate a possible outbreak?
DR. GEORGES BENJAMIN, American Public Health Association: Well, they have very aggressive systems in place to try to identify where these ill patients are. One, having a range of people to report it -- school teachers, principals, public health workers in communities, doctors -- all looking for patients who might be ill by describing the symptoms and having them report to their state and local health departments.
They've got hotlines. They've got e-mail links, a whole range of ways to try to get the word out and get people into the system.
MARGARET WARNER: And, Michael Osterholm, is this kind of surveillance more intense than there would be, say, just for a serious regular seasonal flu outbreak? What's involved here?
MICHAEL OSTERHOLM, Center for Infectious Disease Research and Policy: Absolutely. It is much more intense. What we're actually doing right now is using the fact that most of these cases, in one way or another, had a primary contact with someone either who went to Mexico or a contact of a contact of someone who went to Mexico, so we're actually following up on these cases in an attempt to stop the transmission in a given community by circling that case, making sure we know who the contacts are, getting the medication, Tamiflu or Relenza, to these people in an appropriate time, and then just trying to basically take people who are sick and make sure that they're not out in the community to hopefully limit this virus from moving from person to person.
MARGARET WARNER: And, Mr. Osterholm, staying with you, what about Tamiflu and the other antiviral drug? How much does the United States have? And who should be getting it?
MICHAEL OSTERHOLM: Well, actually, the really good news is that, over the last five to seven years, there's been an intensive effort on the public health community's part to better prepare for a potential pandemic in the future.
Today we have almost 80 million treatment courses in this country, enough for one-fourth of the population, that could be used during a pandemic. Right now, I think that it's fair to say that, while this stockpile of Tamiflu has been moved to certain areas where activity is occurring, for most of these patients, the illness is quite mild.
And, you know, we don't want to waste a lot of this Tamiflu on milder illnesses. So there is some decisionmaking going on, who should get it, when they should they get it.
But one of the also important aspects of this is, when we do give it, it also is an attempt to help stop the transmission of the virus from occurring. So I would say it's limited use right now relative to the fact we have few cases and few contacts that we're treating.
MARGARET WARNER: And, quickly, do you take it prophylactically, say, if you were going to Mexico?
MICHAEL OSTERHOLM: You can take it prophylactically. The actual virus that we're dealing with is sensitive to this, meaning that it's -- the treatment were to be effective against it. And we know from seasonal flu research work that you can actually take this drug in advance of exposure and also ward off the infection.
MARGARET WARNER: So, Dr. Benjamin, now, what about closing schools? Let's take that as an example. What do public health authorities look for in trying to decide whether to close a school?
DR. GEORGES BENJAMIN: Well, there is certainly broad national guidance. And what the intent is, is to try to break the cycle of infection.
So if you have a confirmed case or a suspected case, current national guidelines are to strongly consider closing the school. But it is a local decision, and there are a lot of other things that go into making that final decision.
MARGARET WARNER: Now, as we've pointed out in the taped piece, the Fort Worth school district closed the entire district, 144 schools, after one confirmed case. Would that be considered advisable? Or is that a little overreaction?
DR. GEORGES BENJAMIN: Well, you know, we don't know what went into their decision making process to do that. But, again, some of the things -- reasons for doing that would be where the kids came from. What other kids were exposed? Was there an epidemiologic link to other kids in other schools? How long ago that it was since they were diagnosed with having this disease and how many other people they may have been exposed to? So a lot of decisions in that process.
MARGARET WARNER: And what are the triggers for closing other kind of big public gatherings, I don't know, a theater, a concert, or a sports event?
DR. GEORGES BENJAMIN: Well, you know, certainly, if they're linked to a student from that school. So, certainly, if you've got a football game, for example, that you're playing in that weekend and you close the school, you're more likely not going to have that football game.
But generally we're not yet closing big events in the community unless we have a lot of flu in the community.
MARGARET WARNER: Now, Michael Osterholm, who was right today, Vice President Biden or Transportation Secretary LaHood, on this question of traveling in -- whether it's an airplane or a subway where you're in close contact with other people? Is that a risk? Should individuals avoid that?
MICHAEL OSTERHOLM: Well, I think both of them are right, and it's a teachable moment. And what I mean by that is, is that, as Dr. Benjamin just pointed out, if we look at school closings or whether we're talking about subway riding or riding on airplanes, it's all going to be dependent upon what the circumstances are with the infection.
And right now, we are in a very, very, very early stage where we're not even sure that we will have a pandemic. At some time, it may be necessary or it may be important not to ride on an airplane or on a subway or close lots of schools. Right now, that's just not the case.
And so that we have to get the message out as we have to proportion our response to what the risk is. And the risk is very limited right now, but this is a fluid situation, and that's the whole message of the Centers for Disease Control and Prevention.
Stay tuned. We'll take the messages that we have. We'll take the advice we have, and we'll tailor them to the science. And so far they've stuck to that very well.
MARGARET WARNER: And so, Dr. Benjamin, for an individual, how else can an individual take care not to contract this? I mean, we've all heard about washing your hands, staying home if you're sick. What else?
DR. GEORGES BENJAMIN: Well, you know, Grandma was right. And you go back to reiterating what you said. It's hand washing, hand washing, hand washing; keeping your facilities reasonably clean; cleaning doorknobs; cleaning keyboards; cleaning things that you share with others; avoiding others who are coughing or sneezing.
If you're going to cough or sneeze, you know, kind of cough into your elbow. Don't cough into your hand. These are very, very simple hygienic measures that are very, very helpful.
MARGARET WARNER: And should people be avoiding at all large group events?
DR. GEORGES BENJAMIN: I think unless -- you should follow the public health guidance on that, but I'm telling people to go out, go to the theaters, get on airplanes, get on buses.
But we know that, if the public health community sees that there is a large percentage of people in that community that have an infectious disease that's respiratorily transferred, then we're going to probably close some of these things.
MARGARET WARNER: Michael Osterholm, yet today Secretary Napolitano, the homeland security secretary, said, when she was talking about if your children are sent home from school, don't let them go to the mall with their friends. That's not the idea. So how does that jibe with the notion that we shouldn't necessarily be avoiding social contact?
MICHAEL OSTERHOLM: Well, again, think about why the school was closed. And if it really is an appropriate exposure situation -- meaning that there are children in that school who are infected with the virus and others who may have been exposed -- what we're trying to say is, we don't want those children who might be coming down with influenza out in the malls, exposing other individuals.
We know that this virus can be transmitted some hours before you actually become clinically ill. And then, of course, after you become ill, it can readily be transmitted, so that's very different than saying, "Don't go to the mall."
For the vast majority of Americans -- we're talking 99.99 percent -- we're saying, you know, proceed on with your life as usual. What we don't want to do is have people become overwhelmed and inundated with these recommendations now when they're not necessary and then not take them seriously if and when we start to see that increased transmission that would suggest, yes, now is the time to say that. Don't go to the malls or don't get on an airplane.
And so all we're trying to do, really, is get the message out. These might at some point be necessary, but right now they're not. Let's move forward and understand that we're watching this very carefully.
MARGARET WARNER: Michael Osterholm, Georges Benjamin, thank you both.
DR. GEORGES BENJAMIN: Thank you.