Press Briefing Transcripts

July 24, 2009, 11:30 a.m. ET

Anne Schuchat: Good morning, everyone. Thanks for joining us. You know, today I want to, again, give you a snapshot of what's going on with the new 2009 H1N1 influenza virus but also talk just a little bit about seasonal influenza as well. I'm planning to give you an assessment of what's going on and what we're doing to be better prepared for an increase of illness in the fall.

And today we actually are releasing the influenza vaccine recommendations, so I want to mention those briefly. Those are available at our web at www.cdc.gov. We release every year at this time the seasonal vaccine recommendations. We look at the illness and you'll end up with updates to recommendations. And there are a few updates this year that differ from the past. So let me just highlight those.

First, I want to remind you that while we're focusing a lot of attention on the 2009 H1N1 influenza virus, we do expect seasonal influenza viruses to circulate as well, and we need to be prepared for both of them. The new seasonal influenza vaccine recommendation include a recommendation for annual vaccination for children age 6 months to 18 years. This past year's recommendations encouraged vaccination, and the plan has been that this year this would be a full recommendation. No longer just an encouragement or "where feasible," but a full-out recommendation. The update also includes the strains that are part of this year's flu vaccine and your, of course, new strains for the A H1N1, A H3N2 and B strains. They're all Brisbane source strains that are in the new flu virus vaccines. Vaccination against seasonal influenza should begin as soon as vaccine is available and continue throughout the influenza season. At this point, 83% of the population is recommended to get an annual flu vaccine and we recommend it for anyone who wants to reduce their risk of flu. Unfortunately, only about 40% of the U.S. population received the flu vaccine last year, so we're really recommending an intensifying use of this vaccine because it does protect against illness and complications like hospitalization and severe outcomes.

I want to make a special reminder to health care workers. We have recommended health care workers get the seasonal flu vaccine for years and we all need to be with vaccination coverage. This year in particular we want to keep health care workers healthy at work able to care for sick patients, and we don't want them to be spreading influenza to their patients. We recommend them strongly to receive the seasonal flu vaccine. And I'm expecting when H1N1 vaccine recommendations come out it's very, very likely health care workers will be in that group that ought to get vaccines as well.

Let me turn to the H1N1 situation and summarize where we are. We are continuing to see transmission here in The United States in places like summer camps, some military academies and similar settings where people from different parts of the country come together. You know, I think this is very unusual to have this much transmission of influenza during the season, and I think it's a testament to how susceptible people are to this virus.

We as a country or as a population have protection.

(I believe she must have said that we as a country or as a population have NO protection.)

So in these special circumstances, like camps or close quarters in the military academies, we're seeing the virus spread.

This week we have posted the latest numbers for case counts, but I want to mention this will be the last where you will see that kind of reporting. Our website shows, as of today, 43,771 laboratory identified cases of the new H1N1 virus. And 302 deaths that have been reported to us here from The United States. But as we've been saying, that's really just the tip of the iceberg, so we're no longer going to expect the states will continue this individual reporting and we're going to transition to other ways of describing the illness and the pattern.

On our website you can see something called "FluView," which goes through much more detail about what's happening in different parts of the country. We believe there have been well over a million cases of the new H1N1 virus so far in The United States. And the patterns that we're seeing right now are 20 states reporting widespread or regional influenza activity. As I said, it's very unusual for that kind of illness to be occurring at this time of the year. The Novel H1N1 viruses are making up 98% of all the subtyped viruses we have, subtype influenza A viruses, and we're seeing them dominate here in the U.S.

But I want to turn to the southern hemisphere where a lot is going on. You probably heard about this in the media. We're working closely with partners in the southern hemisphere and the Pan American Health Organization. The new H1N1 virus has been found in many countries, including the southern hemisphere. The specimens we have tested, including from southern hemisphere countries, have not changed. They're still the same strain we're seeing here, meaning that the vaccines we're working on preparing is directed against the strain that is still active both here in the U.S. and in the southern hemisphere countries. Of course in the southern hemisphere, they're having their regular flu season together with the new H1N1 virus, and we're seeing the strain circulate together with seasonal strains in some places and we're seeing it dominate in other places. We are in regular communication with our international field staff and partners in a number of places. There are variable reports about how bad are things in one country or another or in different parts of the country, and I want to mention why that is. Often there are differences in testing practices, in who is actually being confirmed to have this virus. There are differences in health care in terms of how people are managed in the hospital or intensive care unit and what kind of supports are available. There are differences in reporting. In some places, we're hearing about only the severe cases. In other places, we're hearing about illness that's in the community. Based on the information that's been shared with us and the laboratory findings and our people on the ground, we think that the circumstances are quite similar in different places and that this virus is capable of causing a range of illness. Severe life-threatening disease that requires intensive care unit and mechanical ventilation and also milder illness that gets better on its own. And this is really important for people to know this virus is out there, it's circulating, it causes a range of illness and we in The United States have to get ready for the fall.

I want to mention a few words about summer camps because a lot of folks have kids in summer camps right now. We hope parents send their children to sleepaway camps for their children to be looking forward to. A lot of camps have been reporting outbreaks. We've been working closely with camp organizations and state and local health departments to provide assistance to camps to make sure they have good plans in place to keep sick children away from others, to communicate frequently with parents about what's going on, to make sure kids are able to wash their hands often, which is so important in keeping infections from spreading, and that they have good notification processes. Now, in the media there have been reports of some places offering a lot of the Tamiflu or anti-viral prophylactics. I just want to remind you we have guidance about anti-viral medicines on our website. We greatly value the anti-viral drugs. At this point we're strongly recommending them for treatment rather than for prevention. And for treatment of people with complicated influenza, severe presentations or people with underlying factors like asthma or pregnancy that might give them a much harder time battling influenza. There is a place for preventive use of these drugs, mainly for the very high-risk people who are in extremely close contact with someone with the virus. So the anti-viral drugs are one part of our armamentarium for influenza, including the H1N1 virus, but there are other steps that are more important, like keeping sick people home or separated from other people and making sure there's good hand washing and hygiene.

Yesterday we provided a little update about the clinical patterns that we were seeing with the H1N1 virus. There was a report about four children who had severe neurologic complications. Fortunately, most of these children have done well. But it's just a reminder that seizure, encephalitis and other neurologic complications can occur in influenza. This is reported in the literature -- quite a bit for seasonal influenza -- and now it's also occurring with this new H1N1 virus. We don't know whether neurologic problems will be more common with this virus, but we want clinicians to be on the lookout for that and to think about testing and treating for influenza in such circumstances. We know that neurologic problems like seizures are very concerning for parents and we want them to have this conversation that that is one more thing to be on the lookout for in conjunction with influenza. And another reason that we're taking this new H1N1 virus so seriously, in terms of what we're working on and the things that we're busy preparing for, there's a lot of work going on at CDC, HHS and across the government to be ready for the fall.

One area that we're working closely on is school guidance. We had issued school guidance last spring about the approaches to managing influenza in schools, and we're working now to update that guidance. And so I just want to let you know to look forward to formally updated guidance in the next few weeks. We're in the process of reviewing all the information learned from the spring and what are the benefits and unintended consequences of school dismissals, and what are the best ways to keep kids healthy and learning and to minimize disruption, as well as to minimize the real impact that this new virus can have.

A second area that's very active is the efforts around vaccines. I think the media heard yesterday from the FDA and the NIH about efforts being carried out around clinical trials and vaccine development. And I want to remind you that next Wednesday, July 29th, CDC's Advisory Committee On Immunization Practices will be convening here in Atlanta. They will be deliberating recommendations for which populations should be targeted for the H1N1 vaccine and whether prioritization is going to be appropriate. We also provided planning scenarios to the state and local health departments so that they can be working carefully with the private sector, with the health systems, with communities and communicators about vaccination preparations. At this point the secretary has announced that we are planning for a voluntary vaccination program in the fall, assuming availability of appropriate vaccines and that the virus hasn't changed so substantially that a vaccine wouldn't work. So there's a lot going on to be ready for such an effort. And this ACIP committee meeting next week will be a key step in that process. At this point I want to stop and be able to answer the questions that you have which we can go to now.

Tom Skinner: This will start the question and answer period.

Operator: Thank you. At this time if you would like to ask a question, please press star 1 on your touch-tone phone. Please announce your name. Our first question is from Marian Falco, CNN Medical News. Your line is open.

Miriam Falco: Hi. Dr. Schuchat, thanks for taking the questions. Would you say that, especially given the information we got from NOWR on the neurological problems, would you still characterize this strain of flu being mild, causing mild and moderate illness, or is it more severe than that?

Anne Schuchat: I don't like to use the word "mild" for the new H1N1 influenza virus. I actually think this is a virus that's capable of causing a spectrum of illness that includes severe complications and death. Each person is different and each person experiencing this virus has a slightly different scenario. We've seen people with high fever and cough and respiratory illness and really not able to do much more than four or five days. Then we've seen people who have difficulty breathing, severe respiratory failure and need to be in intensive care unit for weeks. So I think there's really a spectrum. The neurologic features that we heard about in the NOWR yesterday are just the reminder of the many ways influenza can cause disease. Of course this new strain of influenza is causing some of the complex presentations as well, encephalitis, high fever and seizure. So I think, you know, it's very important we take this virus seriously.

Operator: Next question. Mike Stobbe, Associated Press.

Mike Stobbe: Hi. Thanks for taking the question. And I'll have a follow-up. First, Doctor, could you just discuss the expectations CDC has for how many cases you'll be seeing in the fall and speak to the importance of the vaccine, what kind of difference it could make and how many kids you're seeing. Yeah, go ahead.

Anne Schuchat: Thank you. Influenza is very difficult to predict. And a new strain like this 2009 H1N1 virus is even more complex. We are trying to make estimates based on what we saw in the spring, what we have seen in past pandemics and what we see in a typical year of influenza. Even with seasonal influenza, with strains year in and year out we see variation year on year. I can't give you an estimate how many people will be ill, what proportion of the population will have influenza illness or need hospitalization or die. What I can say, though, is that vaccination is one of the best ways to prevent influenza and its complications. That's why we vaccinate intensively for seasonal influenza and why we're working on having a vaccine available in the fall for this new virus. We know influenza vaccines are not 100% effective. So your second question is what kind of impact we might have with vaccinations. Vaccination is just one part of the interventions we have available to us. We have efforts that can be directed at the community and individuals, keeping people who are sick away from other people using anti-viral medicines for treatment, and of course social distancing efforts like occasionally school dismissals or mass gatherings cancellations. Those kind of interventions are used in different circumstances depending how bad things are and how much benefit you think they may offer. But vaccine is a very important part of the intervention tool kit. And the influenza vaccines tends to be more effective in healthy young people than they are in seniors. This particular H1N1 virus seems to be more of a challenge for healthy young people and for adults who aren't elderly or underlying conditions. So our expectations are that a vaccine against this would probably work in a similar fashion to the seasonal flu vaccines. Next question.

Operator: Next is from Maggie Fox from Reuters. Your line is open.

Maggie Fox: Hi, Dr. Schuchat. I'm sorry to ask you to do this because you say you don't like to say how many but the million number is getting kind of old at this point. We're trying to explain to people all around the world how many might truly be affected so we can get away from the count thing. Is there a better estimate how widespread this is likely to be, given that we have 500,000 deaths every year from seasonal flu which suggests many tens of millions are affected.

Anne Schuchat: For The United States for seasonal flu we have about 36,000 deaths and about 200,000 hospitalizations. And we think that millions and millions of people are affected. Probably 20 million or more people are infected every year with seasonal influenza viruses. What I can tell you that we know right now is that in communities where this particular virus has circulated, we saw community attack rates of 6% to 8%. But this virus didn't circulate everywhere this past spring. We had the 6% to 8% attack rate just during the spring months. So we think in a longer winter season, attack rates would probably reach higher levels than that, that we would see quite a bit more than that. Maybe more two or three times as high as that. So I think that when people are trying to really get their arms around just how bad this will be, what I like to say is that we need to be ready for it to be challenging. We have lots of ways that we can limit the impact that it has, but it's going to take us working together. We know that our emergency rooms are often crowded in the regular year, and particularly in the winter season they can be crowded. This particular virus might crowd the emergency department season more. So one of our goals is to work with the medical community and the population to help people know when you don't really need to go to the emergency department and when you do so we can free those up for the most relevant cases, the cases that really need management there. And so unfortunately with influenza we just can't put numbers down to this. I suspect years after next year we'll have a good idea exactly how large the impact was and how much we prevented through the efforts that we work.

Tom Skinner: Maggie, do you have a follow-up?

Maggie Fox: That was a nice answer, but I still think the millions numbers isn't, you know, over a million is not terribly informative. And I know we have 20 million in a regular flu season. Would it be misleading to say, you know, more than 10 million? More than 20 million?

Anne Schuchat: That we're expecting, you mean?

Maggie Fox: Yeah -- no.

Anne Schuchat: No, that wouldn't be misleading to say that.

Maggie Fox: That have been infected already.

Anne Schuchat: That would be misleading. I'm sorry. That would be misleading. I don't think it's that high. The more than a million estimate was actually based on a modeling effort. And what we're trying to do is refine that model. So I hope in the weeks ahead we'll be able to share with you a little bit better figure of what we think has happened so far. we're actually working on this, have gotten some good feedback about some of the assumptions and the ranges, and we're trying to really make this model as strong as possible before we share it more publicly. so that's really -- I do think we'll be able to get you what you need in a couple weeks. I'm sorry. I misunderstood.

Tom Skinner: Next question, please.

Operator: Next is from Lisa Stark with ABC News. Your line is open.

Lisa Stark: Thanks so much for taking my question. I'm unfortunately going to talk about numbers too. You know, as you heard an AP story saying you have a worst-case scenario, if the vaccine doesn't work and other measures aren't successful there could be as much as 40% of Americans infected and several hundred thousand deaths. Can you comment on this worst-case scenario and what these numbers are that you're working on in that regard?

Anne Schuchat: We are planning for the most likely scenario and also for more severe scenarios. Worst-case scenarios we don't want to take us by surprise. With the pre-pandemic planning that we did the last several years we spent time focusing on pretty severe scenarios, like 1918, where the H5N1 virus that had 60% fatality with it would take off and be transmissible. So much of our framing has been focused on the very severe impact where 40% of the workforce might be absent because they're sick or staying home to care for a sick person. A more likely scenario, which is the kinds of patterns we saw in the spring in the most affected communities like New York City or Seattle, for instance, are seen in more general -- in many, many communities or really across the country. And that scenario is also, I think, challenging. You know, because I know that people read about this about New York City, Chicago, Seattle, and some of these areas, many children were sick. They were outbreaks in schools. Some of the schools were closed. Emergency departments were busier than they wanted to be. It was hard for people to get the care that they needed, and the information needs were very, very challenging. So planning for that more likely scenario where other communities discuss that disease transmission is a big focus for us and we think that we can limit somewhat the illnesses and severe complications of that kind of virus circulation with updated guidance, with partnership between the private and public sector, and of course with the efforts that we're making towards development of the vaccine. So those planning scenarios talked about, you know, talked about something like 40% of people missing work and how do we cope with that in society. But right now we're not expecting that high an absentee rate, but we are expecting challenges.

Tom Skinner: Lisa, do you have a follow-up?

Lisa Stark: But is it true that based on the pandemic of 1957 that, you know, if you had a worst-case scenario that you would have 40% of Americans who would have gotten the flu and maybe several hundred thousand who would die. Is that what you're thinking, could be, in fact, the worst-case scenario?

Anne Schuchat: I think we really need to get back and say worst-case scenario planning has a couple different assumptions in it. It talks about what proportion of people are ill, what proportion of people have very severe illness requiring hospitalization or leading to death, and what proportion of people are disturbed by the frequency of illness, need to stay home to care for others, or are impacted because their job is closed because the workforce can't remain open because of illness. So worst-case scenario is looking at the different sectors and see how extreme could things be. One of the values of worst-case scenario planning is it helps us think about continuity of operations. It helps people figure out is there anybody besides me at work who knows how to do the stuff that I do? Because what if I'm home ill or staying home with my child for a couple weeks, how will our workforce keep functioning? Who knows how to do my job? But worst-case scenario planning isn't the only important thing. It's very important we plan for what is quite likely. Based on what we saw in the spring and in the southern hemisphere, we think there's a lot of planning we need to do around what is likely. So this is a very important message. Things don't have to change for us to have a lot of work to do, for each parent and each person to be thinking about getting ready for how they're going to manage their child when they're ill, who can take care of my child if I can't stay home with them. Are are there others at work who can do what I do because I'm staying home with my child. How will I get information from school or the local health department about where to go or what I need to know. These are preparedness steps that everybody can take. And we think things don't have to change at all for it to be time for people to think ahead about being ready.

Tom Skinner: Next question, please.

Operator: The next question is from Tom Maugh of the Los Angeles Times. Your line is open.

Tom Maugh: Hi. The schools are going to be opening in the east at least within the next month well before any vaccines are going to be available. This suggests that this new flu is going to be pretty firmly entrenched in the population before vaccines come out. How much good are the vaccines going to do then?

Anne Schuchat: That's a very important question. We do think that schools reopening will lead to increases in illness in some places. Of will it be in every school? I really don't know. I don't think it's too likely that every single school is going to have problems. What we saw in the spring was patchwork. Some communities had a lot of disease and others didn't see any really. I think that schools will be reopening at different times over the next several weeks. And we want them all to be ready, but we also know that influenza is so unpredictable. It can just skip communities altogether and it can really affect some communities quite hard. So what we're trying to do, working with the department of education and working with the state and local governments as well, is to strengthen our ability to manage. You know, it's -- we're going to be updating school guidance, but it's very important for people to know that the local and state levels really are in charge of the school programs in their communities. What we're doing now is looking across the spectrum of what happens in schools, how do we keep kids healthy and learning and sick children home and away from other students. How do we make sure that we have provisions around school lunches and around the various supervision and education functions that occur in our schools. So we're really -- there's a lot that we can do even before we have a vaccine available, for instance, to make sure that kids are healthy and learning. And that's really where the government is focused right now.

Tom Skinner: Do you have any follow-up?

Tom Maugh: No.

Tom Skinner: Okay. Next question.

Operator: The next is from Donald McNeil, New York Times. Your line is open.

Don McNeil: Thank you. So, are you specifically bluntly recommending that summer camps stop handing out prophylactic Tamiflu to their campers? Are you doing anything to stop them? Are you calling summer camp associations or pharmacies and asking them to stop or cut off?

Anne Schuchat: I don't think that's a good idea, the prophylactics to all campers. What I can say is we have guidance about anti-viral medicines and the best ways for them to be used. We've been working closely with the camp associations and with the health departments who work locally with their camps, and we really want the public to know that anti-viral medicines are important. They're part of our armamentarium. I think another important thing to say is we have the resistance to Tamiflu in the new virus. I believe now there are about five cases that have been reported that are Tamiflu resistant. That's a very small number compared to the very large number of cases we're seeing around the world. But we have seen with other influenza viruses them taking off with a low level of resistance to virtually all strains being resistant. We think it's important to be careful about how the medicines are used but there are circumstances where preventive use of anti-virals is still important in people who have severe medical problems, who have been in very close contact with someone with influenza. So I think our efforts are really trying to make sure people know the right way to use the medicines, the role that they play and the risk of resistance that's out there that we don't want to get any worse.

Tom Skinner: Next question.

Operator: The next is from Joanne Silberner. Your line is open. From NPR.

Joanne Silberner: Thanks. And I hate to plague you with numbers but got to do it. Follow-up on the 40% of Americans over the next two years. That number, that's the number who may be affected in terms of they themselves are ill or people around them are ill and they're caretakers? And the second question is earlier you said the attack rate in communities was 6% to 8% with this flu. How does that compare to seasonal flu?

Anne Schuchat: Okay. The 40% figure that I gave was not about illness. what I was trying to say was our planning assumptions for a severe pandemic were that at a certain period up to 40% of the workforce might be affected and not able to work either because they were ill or because they needed to stay home to care for an ill family member. So a lot of that is the ill family member, not the worker themselves. The second question that you asked -- I'm just forgetting what it was. I'm sorry.

Joanne Silberner: How does the 6% to 8% attack rate compare with seasonal flu?

Anne Schuchat: It's difficult to compare that. One reason that it's difficult is that 6% to 8% attack rate occurs in the May to June period when there was zero cases of seasonal influenza. To some some extent we were seeing a lot of transmission when the circumstances weren't that great for transmission. During seasonal influenza, the winter months, we might see rates of 10% to 15% of people developing influenza-like illness. And so what we saw in that sort of three to four-week period with the 6% to 8% was probably just a glimpse of what might happen over the longer winter season when transmission circumstances like temperature are different. So it's really an apples and oranges comparison.

Tom Skinner: Next question?

Operator: The next is from David Brown, Washington Post. Your line is open.

David Brown: Yes. Thank you very much. Two unrelated questions. One is, has CDC done any modeling in which they have taken the clinical characteristics, to the extent they're known of this virus, attack rate, case fatality rate and said, okay, if it peaks in let's say mid-October and there's essentially no vaccine protection, what is likely to be the effects on the population in terms of number of cases that are severe enough to be hospitalized and the number of deaths? So that's my first question. My second question is, can you talk a little bit about camps and the military academies. How many camps? Which military academies? What the attack rate is there. Whether you've been studying them closely to try to get a better sense what the epidemiology is. So a few details about these recent outbreaks.

Anne Schuchat: The first question about whether we're modeling to try to estimate the impact in October and so forth, we are working on that. I don't have numbers today to be able to share. But that's the type of effort that we're making. There's a lot of modeling that's going on around the world and around the U.S. with academics, investigators and the number of institutions. They have been meeting with us to plug our data into some of these modeling efforts. What I believe is that we will see a range of estimates to come from these. It's very clear when one is doing these modeling efforts that there's some information that is pretty hard and fast and there's others that's really expert opinion or best guess. And some of the most important factors may be ones that we really don't have hard estimates to plug in. But I think these are really important efforts and they'll help us really put some limits around the range of possibilities. But I think we do have to be -- you know, it's very difficult to be comfortable with uncertainty. And I don't know the reporters today want much to be much more crisp in my predictions. But I think there's models are only going to be precise -- these models will not be precise. We think it's important to step back from a focus on a single number and sometimes even a range around the number is much less precise than we need. I don't think that influenza and its behavior in population lends itself very well to these kinds of models.

The second question was about the military camps. I don't know whether we have active investigations going on. That's something I can check on. But I'm not aware we're assisting -- I'm certain that -- I know there are a number of reports we heard, but I don't have the information about whether we're actually helping with some of the investigation.

Tom Skinner: Next question?

Operator: The next is from Stephen Smith, The Boston Globe. Your line is open.

Stephen Smith: Hi, Dr. Schuchat. Thanks for taking the call. I was hoping to get a better sense when you were talking about the summer camps and prophylactic use of Tamiflu what your sense was into how widespread that is, whether -- and additionally whether you have sent any investigators out to investigate clusters of illness at summer camps and, if so, in what parts of the country.

Anne Schuchat: You know, summer camp situations are quite different than schools. One thing I want to say is that we have been in touch through the states and local health departments about the camp situation. We have had heard reports on prophylactics, and on further probing we did not find that to be the main response -- the common response. We didn't find that to be typical or what everybody was doing. I know there have been media reports about individual camps who have taken that route, but that wasn't the typical response we've heard of.

A thing about summer camps that's quite different than school scenarios, is they're a lot shorter. They're usually one- or two-week experiences and you have a high turnover. So the circumstances for investigation are often not that stable. We did a number of field investigations with schools in the spring to try to understand the population, what was going on and what interventions were working. But the way things are usually quite short-lived in the camps, I don't believe we've actually sent teams out. The health department is really the front line of public health out there are actively working with camps in their jurisdictions to make sure good information is available and that they're able to help provide guidance. so I don't believe we've been, you know, in a field on the camp situation.And it is not a fixed population that is managed over the months. It's a shorter-term population.

Tom Skinner: Next question?

Operator: The next is from Steve Sternberg, USA Today. Your line is open.

Steve Sternberg: Hi. Thank you very much. I'm wondering how much is known about resistance in the Novel H1N1 virus. There were cases in Asia and Europe, as I recall. Do we know anything more about them and whether -- are there any cases in the U.S. now?

Anne Schuchat: At this point what we're aware of is five cases have been reported either by the WHO or by the countries. One of these five cases was detected in Hong Kong, but it was an American who was traveling there from San Francisco. And the assumption was that the person probably acquired the infection in San Francisco. An investigation was done in California around that to understand whether there are influenza viruses circulating in that area that are resistant. Large specimens were tested and no other resistance was bad. It could be that are Tamiflu resistant circulating in the U.S., but so far the only one report that we have is of a traveler from here who went to Hong Kong and was tested in Hong Kong. You know, this is something that should not surprise us if we see more and more of this. This is, you know, influenza viruses mutate frequently and any viral resistance could be acquired easily. Most of the cases that were detected so far, most of them occurred in people who were taking anti-viral Tamiflu because they had been in close contact with somebody who had the disease. The good news is none of them spread it to anybody else. Some of the investigation involved testing their contacts and they didn't see any evidence of spread or, you know, passing that along. But I think it won't surprise us if we see resistance emerge as a bigger problem in the fall or in the years ahead. As I mentioned with the other two influenza viruses, this has been a problem. The seasonal H1N1 viruses right now are virtually all resistant to Tamiflu.

Tom Skinner: Next question.

Operator: The next is from Jon Cohen, Science Magazine. Your line is open.

Jon Cohen: Hi. Thank you for taking my call. I think there's a lot of confusion about clinical trials. Two days ago five trials did not have adjuvant. They said there would be tests with adjuvant. The companies have spoken of doing clinical trials with adjuvant. The government has purchased it with a separate ingredient that can be mixed and matched. What is the plan for doing clinical trials with adjuvant?

Anne Schuchat: They are planned. They're a set of -- there are several different ways that the trials get summarized. The NIH or National Institute of Allergies and Infectious Diseases is coordinating a set of studies with their vaccine, treatment and evaluation units around The United States. And those are a set of trials that I believe that are listed on their website. The manufacturers will be doing trials in collaboration with the FDA. And of course there are trials being done in other countries on behalf of those other countries vaccine planning efforts. The U.S. has purchased adjuvant as well as antigens and we are expecting to see results from trials of how well adjuvant works in terms of changing the immune response to a given antigen. I don't actually have the details of how many trials with adjuvant and the timelines for the trials but there are definitely plans to look at the behavior of this -- of the vaccine when it is adjuvanted.

Tom Skinner: Next question?

Operator: The next is from Kate Ryan, WTOP radio. Your line is open.

Kate Ryan: Hi. Thank you. I'd like to kind of backtrack a little bit on the concern about school populations. And you mentioned earlier for seasonal flu recommendations going from encouraging parents to have their children vaccinated to recommending -- a flat-out recommendation. What's the difference, and do you see a time when schools should be advised to say, if you don't have your immunization, if you don't get these kids vaccinated we're not going to let you in?

Anne Schuchat: The comment I was making about the recommendations were for the seasonal flu vaccine. So I want to make sure everybody is aware of that as I go forward. So my next few sentences will relate to seasonal flu vaccine recommendations. The advisory committee for immunization review practices looks into the question of whether vaccinations should be broadly recommended for school-aged children. And it was a multiyear process. They reviewed data on the burden of disease, the direct and indirect benefits of vaccines, the feasibility and problematic concerns, the cost-effectiveness, vaccine behavior, how well the vaccines were tolerated in terms of their safety profile, short and long term. They looked at all factors. And when they voted on recommendations for school-aged children, one of the critical factors that was discussed was that this wasn't something that could happen overnight, that it might take a while to be able to implement vaccination of school-aged children because the logistics are complex and because we don't really have a very, very strong school infrastructure or public health infrastructure for school associated immunization. So what they recommend was a multiyear process that would encourage vaccination of school-aged children where feasible but the recommendations wouldn't be fully implemented until the 2009 season. So we're butting up against that 2009 season for full implementation. And the idea was the last couple years the state and locals were going to be able to start planning how this might work. Of course it has gotten a little complicated this year because the same public health infrastructure is also coping with the new H1N1 virus and working on whether plans will be in place to be able to offer vaccine to school-aged children against that virus, as well as the seasonal flu viruses.

So the second part of your question was about mandates. Mandates for immunization for school entry are a state and local matter. The immunized states, every state mandates use of certain vaccines for school entry, such as measles vaccine. Influenza hasn't typically been a vaccine that has been on that same kind of listing. Measles, of course, is a disease that we have eliminated in The United States. Much of the tremendous control that we've had with measles has been through high immunization coverage, as well as high second dose coverage, which is where the school entry requirements came through. so at this point I am not anticipating mandated influenza vaccine for school-aged children. But whatever happens, that will be a state and local matter.

Tom Skinner: Time for a couple more questions.

Operator: The next is from Rehema Ellis, NBC News. Your line is open.

Rehema Ellis: Thank you very much for taking my call. My question is about vaccine production. Can you speak more directly to exactly how the trials are going and when do you expect the vaccine will be able, and will it be available for every one of the populations you are recommending should get the vaccine?

Anne Schuchat: The clinical trials of vaccine require pilot lots to be produced. So you basically use relatively small amounts of vaccines in order to carry out a clinical trial. And right now in Australia they have already launched a clinical trial and the NIH is about to launch several trials next week, I believe. So the clinical trials will be happening over the next several weeks to months, and that will be providing helpful information right away about how people react within the days after they receive vaccines and later on about their immune responses to the vaccine. Production is also going forward right now. The U.S. has procured vaccines from five companies, and those companies are all taking the steps to make large amounts of vaccine available. They are producing antigen in bulk and at a certain point in the next couple months, decisions will be made about filling and finishing that antigen into actual vaccine that can be given, putting it into vials or put it in open syringes. It's expected that the decision will be made about how much antigen should go into the vials in the months ahead. At this point, the U.S. government has procured large amounts of vaccine but we haven't yet made recommendations on what populations ought to be offered vaccine.

A key step in that process will be next week when the Advisory Committee for Immunization Practices meets and looks through information about the disease burden and the vaccine, expected impact, and the logistics and the risk benefit kind of circumstances, and they will make recommendations on which populations ought to be targeted for vaccination. At this point the planning and investments that the U.S. government made suggests to us that we are likely to have plenty of vaccine for the groups that are targeted. Of course it is always risky to say that because influenza vaccine manufacturing is not always as predictable as you would like. And sometimes we have surprises. But at this point we're expecting there to be a reasonably large numbers of doses available and the middle of October is the point that we're looking at in terms of our planning, that we hope to be able to launch a vaccine program, assuming several factors in terms of safe and effective vaccine is available and no big change in the antigen properties, we're planning the middle of October timeline. The exact number of doses that we'll have, whether everything will be ready to go, those are things that we really have to be prepared for some surprises around.

Tom Skinner: All right. We'll take one last question.

Operator: Marilyn Serafini, National Journal. Your line is open.

Marilyn Serafini: Hi. Thanks so much. I have a question about the vaccine. But I guess the first question -- well, the first part of the question is, is there any evidence at this point that the virus is changing?

Anne Schuchat: We're looking closely at the strains circulating in the southern hemisphere and here and in terms of the vaccine or immunologic properties of the virus, we don't see changes. We look for antigenic changes. That would mean the vaccines we're developing will not be great fits for this particular virus. But so far the virus hasn't changed in those ways. The only change we have seen is that the five cases we've learned about that have the resistance mutation. But that's not a kind of change that would affect the vaccine fit. You had a second part?

Marilyn Serafini: Do you have any expectations that the virus -- what would it take for the virus -- if changes in the virus to make the vaccine not efficient and also how do we look at the people who have had -- have already had H1N1 over the summer or believe they did, because not everyone knows for sure because they weren't specifically test but we assume they did, and how do we handle those people going forward? We know that, you know, there will be limitations to the amount of vaccine that's available up front. And if that is the case, do we know what kind of resistance these people already may have and will there be enough information available to them and to the public health system that perhaps they won't need the vaccine?

Anne Schuchat: The question of what will it take for the virus to change, influenza viruses can mutate relatively easily. And sometimes those changes result in major changes in their antigenic properties. We aren't expecting that to happen between now and when vaccine is veil but it could happen. It's one of the things we're looking at carefully with the virologic testing. The second question is about what kind of impact it would have for vaccination recommendations, if you have already had a flu-like virus that you think was the H1N1 virus. At this point I believe that's the kind of issue that the advisory committee for immunization practices may cover as they come up with recommendations. It's very important to say that most people who have respiratory illnesses don't find out exactly what caused it. Even most people with influenza don't know exactly which type of influenza caused their illness. So it's very difficult to differentiate what my fever and cough were due to on an individual basis. It may just be not possible to say whether the illness that you had in the past several months was truly caused by this new virus. So I believe that the ACIP will be addressing those kinds of questions as they make recommendations, and we hope those will be practical ones that will be helpful to both the clinicians and the people out there looking for vaccine.

Tom Skinner: Okay. We're going to conclude our briefing. Thank you, Rose, and thanks to all who dialed in. And we'll be sure to keep you all informed of future media briefings that we're having. Thank you very much.

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