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CDC Telebriefing on Investigation of Human Cases of H1N1 Flu

May 9, 2009, 11 a.m. ET

 

Operator: Welcome and thank you for standing by.  At this time, all participants are in listen only mode.  During the question and answer session please press star one to request ask a question.  Today's conference is being recorded.  If you have any objections, you may disconnect at this time.  I'll turn the meeting over to Dave Daigle.  You may begin. 

Dave Daigle: Good morning, everyone and thanks for joining us.  I'm Dave Daigle with CDC Media Relations.  This morning we want to provide a brief update on today's call we have with us Dr. Anne Schuchat, director of National Center for Immunization and Respiratory Diseases and Dr. Joe Bresse, Epidemiology and Prevention Branch Chief in our Influenza Division.  Dr. Schuchat will have a short opening statement and then we'll turn it over for questions. 

Anne Schuchat: Good morning and thanks for calling in for this briefing.  I'd like to be pretty brief here and just give you a snapshot of the latest statistics, the trends that we're seeing, and really spend most of the time on your questions.  You know, as we've been saying, we had expected more cases, and we are continuing to find them.  Today there are almost 3,000 probable and confirmed cases here in the United States in 45 states and the District of Columbia.  That's an increase of 494 since yesterday.  The breakdown is 2,254 confirmed cases, and 722 probable cases, and of course, the details are on our website.  There are 104 hospitalized cases and we still, for information about that; we are still seeing quite a few of the hospitalized cases having underlying diseases. 

Our assessment is that transmission here in the U.S. is ongoing, that this is a very easily transmissible virus similar to the seasonal influenza viruses. We've been suggesting that it's less important to focus on these individual numbers in states or the totals, and instead to look really at the trend.  I want to let you know that our regular flu website is at www.cdc.gov.  We have a seasonal influenza web site that uses our routine influenza system; hat's been updated again yesterday.  We update it weekly and there you can see that the impact of this particular virus spreading around the country is visible in our influenza-like illness (ILI) net graph.  You can see an increase in the proportion of doctor visits that are for influenza like illness in this past week that we're reporting.  You can also look there on the FluView map that shows state by state activity.  It's really an aggregate of all influenza activity, seasonal and this new H1N1, but the trends from this particular new virus are showing up in that ILI illness graphics.  We are going forward going to continue to report to you the case counts as we get them, but we will also be reporting those routine systems, data, and I think that can help put this in context. 

You know, the virus is continuing to spread here.  Fortunately, the severity of illness that we're seeing at this point doesn't look as terrible as a category 5 kind of pandemic or the really devastating impacts that some had feared, but as you know, influenza virus is unpredictable.  It can change over time and going forward, it's really important to us that we pay attention to how this virus may or may not change, as it circulates here in the U.S. and around the world, what happens in the southern hemisphere, where they're just heading into their flu season now, and really anticipating what might happen in the fall.  So a lot of our emphasis here in the U.S. is still understanding the epidemiology transmission, severity and viral characteristics, but also working with partners internationally to really prepare and evaluate issues in their countries. 

There are activities going forward across government in thinking through the issues involved with vaccine development, as we've said, we're preparing the vaccine candidate strain to hand off to researchers in industry, and the government will be exploring additional efforts going forward related to vaccine, but at this point, we're trying to make sure that there continues to be the appropriate level of concern for this kind of circumstance where a totally new virus has entered the human population.  We heard in the media and from partners the sense that the all clear whistle has gone off or we're out of the woods, but I do want you to know that here at CDC and in the public health community, active efforts are still ongoing.  At this point, I'd like to open the call to questions that you have.  Thank you, yes, operator our first question, please. 

Operator: The first question comes from Daniel DeNoon, WebMD, your line is open. 

Dan DeNoon: Thank you, Dr. Schuchat.  Do you have any sense of whether, of whether the flu levels from the new flu are of above the epidemic level?  What are you seeing at this level and my second question is, are you getting any results back from serology testing, any sense of what kind of spread you're seeing from this virus?  Thank you. 

Anne Schuchat:  Thank you.  You know, one of the ways we, with seasonal influenza we look, we compare the information against an epidemic threshold, and one of the marketers for that is our pneumonia and influenza mortality that comes from 122 cities, and good news is we are not seeing a rise above the epidemic threshold in that system.  You know, that would be a very worrisome sign especially at this time of year and we're not seeing that.  So the influenza-like illness is increasing above the threshold that we would expect for this point in time.  We know that more people are going to the doctor, we believe more people were seeking health care a week or so ago, based on concern about this, and a higher percentage of doctor visits were for influenza-like illness.  We're collecting viral specimens in that context to understand whether it's seasonal flu or other respiratory viruses or this new H1N1 virus, and in our virologic service we see a new mixture.  The seasonal is circulating through this virus.  Those graphics are on the website under the flu view site you can see that we are starting to be able to detect this issue in our weekly reports and some of which are now daily but a lot of the, the most worry some feature, the mortality one we haven't seen an increase in that. 

Dave Daigle: Thank you, Dan.  Next question please. 

Operator: Mike Stobbe with the Associated Press, your line is open. 

Mike Stobbe: Good morning, thanks for taking the call.  Just an update on how many states have the kits and are doing confirmatory testing and also could you tell me, Dr. Besser had mentioned before we might be seeing some data from CDC on ER visits and doctor visits, some quantifying of that volume.  Do you have any information on that? 

Anne Schuchat: Right.  All of the states have received the kits, and what is happening is more and more of them are validating their test.  They're getting their testing validated to be able to catch up with, you know, to do their own testing.  We also have certain reference states helping others in terms of the validation so I don't believe I actually have the number of states; I'm looking through my materials here.  I don't think I actually have the numbers today are how many states are doing their own testing but I would say it's going to be increasing on a regular basis.  We had been really paying a lot of attention to the backlog in the states and here to try to make sure that we could catch up but again I want to say we want to transition into this period where the seasonal flu types of systems are more helpful.  You had another question about the doctor visits.  Could you just repeat that again?  I lost track of what the question was. 

Mike Stobbe: The volume of ER visits was going up at least for awhile.  Dr. Besser at one point said, if I understood him correctly, the CDC might have some numbers or some quantifying of that.  I was wondering if you had numbers that could let us know for this swine flu how many people have been going to the ER and/or going to the doctor. 

Anne Schuchat: Right.  So the ER numbers I don't have.  There's a system that does try to track that in a few places.  It won't be numbers but it will be above baseline and there's a certain percentage of the ERs where we have data that we're seeing an increase in visits for influenza-like illness.  The information that you'll be able to see on the website, though, shows the doctor visit part of that, that more people were going to the doctors for influenza-like illness and that definitely shows up in our national statistics.  You know, we are above the national baseline for this time of year on a national level, well above it.  You can sort of see everything was going down and then it starts to come up.  But when we look at the virologic characteristics of what is being tested in these kinds of systems we see that it is not all this new strain.  The new strain accounts for a portion of the cases, but similar portion of the cases are the regular seasonal influenza strain, the regular H1N1, the regular h3n2 and the regular influenza b strain, so that we don't see, we're not at a point right now where 100% of the virologic isolates that are tested are this new strain.  That may be viewed as good news that the strain hasn't totally dominated, or you could say it's bad news because the circulating viruses for seasonal flu are still there and that gives us a risk for re-assortment.  So I would say it's an interesting observation and one that we're taking seriously and continuing to follow. 

Dave Daigle: Thanks, Mike.  Next question, please, operator. 

Operator: Next question, Emma Hitt with Medscape.  Your line is open. 

Emma Hitt: Yes, thank you very much for giving this press conference.  What advice do you have for clinicians about the use of antivirals and are you concerned or do you have any evidence that there's a development of resistance to these agents? 

Anne Schuchat: You know, those are great questions.  We have been updating guidance for clinicians and our website will have the most recent interim guidance.  Early on in this situation with a totally unknown new virus we were fairly aggressive in our treatment recommendations.  As we've seen more and more infections and understood the characteristics of illness, we've tried to update the guidance to focus on making sure that severe illness gets treated with anti-viral drugs, that people who have underlying risk factors or complications of influenza such as pregnant women or people with long-term medical problems, that those patients really can benefit from treatment, but that other people probably can get away with self-care at home and so we're really trying to make sure that the anti-viral therapy is available for the severest cases or those in a high risk group.  You know the good news so far is that the vast majority of people seem to have a self-limited illness, you know, a few days at home in bed and then a few days more at home staying away from other people so that you don't spread the virus when you go back to work or school.  The resistance question is also important.  You know, very good news right now that the viruses we've characterized are not resistant to Oseltamivir and sorry, Tamiflu and Relenza.  We have seen changes in resistance quickly for seasonal flu viruses and this is one of our big concerns.  We really want to make sure that we're tracking resistance, because things could change rapidly.  So that's another reason that the focus of our anti-viral drug recommendations right now is on treatment, not prevention, and on treatment in the people who we think may suffer the worst consequences from the flu. 

Dave Daigle: Thanks, Emma.  Next question, please, operator. 

Operator: As a reminder, star one to ask a question.  Our Next question is form Marilyn Chase with Bloomberg news.  Your line is open. 

Marilyn Chase: Good morning.  Thanks for taking my question.  I have sort of a two-part question, if I may, both having to do with vaccine and immunology.  First of all I understand with talking with Dr. Fouche he sent you serum from people vaccinated against the 1976 swine flu to see if those blood samples retained any activity to the H1N1 crossroads we're now seeing.  And do you have any insight into whether since the earlier sporadic cases outlined in The New England Journal this past week which seemed to prompt more severe disease, whether in gaining human-to-human transmissibility, do they find there's been any loss of virulent genes? 

Anne Schuchat: A couple comments.  You know, the serologic, sorry, the serum from the 1976 vaccine recipients is being worked on in our laboratories.  The immunologic that have been carried out so far are very complex and we're the early stages of putting the data together and trying to amass sufficient numbers of results in different population groups to be able to interpret the results and so I would say it would be premature for me to summarize what we know right now, because I think we're not finished with those evaluations.  I think there was another part -- oh, you asked about the virulence markers.  Yes this issue of how do influenza viruses change as they go through populations.  They may in order to be fit and sustaining transmission, they may change some of their properties in terms of mutations and evolving characteristics.  What we know so far is that a number of viral isolates have been sequenced and sequenced information has been looked at carefully by us and by many other researchers.  That information is in the public domain, so that the whole scientific research community, which is the phenomenal engine for this kind of issue, is really attending to that, and the good news so far is that the virulence markers that have been characterized for the 1918 strain and for the H5N1 strain do not appear in the viruses we're seeing.  This H1N1 problem.  That's good news, because we know those virulence markers are bad news, but what we don't know is whether there are other virulence markers either for 1918 or H5N1, there may be characteristics of this virus that have a potential to be more virulent.  What we're seeing epidemiologically the pattern doesn't look like the 1918 strain, but remember that in 1918, the first wave was fairly mild and it was the next wave which was so devastating.  So I think that we can, the absence of those markers is reassuring but not so reassuring that we're not continuing to study.  We are definitely taking this very seriously. 

Dave Daigle: Thanks, Marilyn.  Next question, please, operator. 

Operator: Next question, Maggie Fox with Reuters, your line is open. 

Maggie Fox: Hi, I'm wondering how much of all the attention that we're paying to this, is an artifact of just being able to genetically test this virus.  If this had happened 20 years ago, would we have just been talking about kind of an initially late flu and hmm, interesting, and not much more attention to it than that. 

Anne Schuchat: That's a really interesting question.  We have invested substantially in strengthening our surveillance, strengthening our laboratory capacity, and strengthening our global partnership, so that when increases in pneumonia in Mexico occur, the global community can know about them and try to contribute, or so that when unusual viruses emerge, we detect them early.  We know that there have been bad problems in the past, when emerging infections smolder.  I think back on what would have happened, had we recognized HIV much, much earlier and been able to respond.  So I think that the question of whether we are ahead of things because of those investments and responding to those, a new virus more aggressively than we might have 15 years ago, I do think we know about this problem earlier than we might have, but that's really the value of the investment in preparedness that, had we known, if we end up having a bad pandemic of influenza from this strain, we will have had a real jump-start on issues like vaccine development and production and prevention and preparedness.  So I think that there's this tradeoff of a signal that you respond to versus responding to everything.  This particular virus had all of the hallmarks that we look for with a possible pandemic, a totally new virus, capable of causing disease in people, capable of causing disease that's serious in terms of death, and ease of transmission.  So all of those characteristics are the ones that you look for in a possibly pandemic causing strain, and I think that's really why we've been reacting.  Might we have never even realized we had a problem, I'm not sure.  We're certainly, you know, mindful that there's a balance. 

Dave Daigle: Thanks very much, Maggie.  Next question, please. 

Operator: Next question is from Deb Krausnick of CNN.  Your line is open.  Deb Krausnick, your line is open. 

Deb Krausnick: Sorry, I forgot to hit mute back.  We got an e-mail saying that Vermont has just confirmed a new case.  Do you know if that's Vermont's second case or if that's been confirmed by the CDC?  Anything about that? 

Anne Schuchat: No, I don't have that information, but I'd encourage to you contact the Vermont health department.  The other thing is that our website as of 11:00 a.m. every day lists the confirmed cases by state, so that will show you, you know, how many in Vermont are confirmed as of 11:00 a.m. today.  I'm not -- it is two?  Oh it's one.  As of 11:00 a.m. today our website is showing one case confirmed in Vermont.  So I think as you know we're only updating that once a day because there's testing going on in the states as well as here.  Things are very fluid and again, the individual numbers we think are less vital than the trend.  You know, I think an important point to say is that we think that this virus is in most of the United States and its arrival is a wake-up to evaluate what's going on, but that the individual numbers are likely a very great underestimate of how much virus is circulating or how many people are becoming ill from this.  We do know, we are now trying to focus on the severe illness that's occurring that may be attributed to this virus, and the trends.  So I know that it's in every state it's really easy to focus on the numbers but I think right now the numbers don't tell us as much as the trends. 

Dave Daigle: Thank you.  Next question please, operator. 

Operator: Next question, James Unland, editor of Health, Business and Policy, your line is open. 

James Unland: Thank you very much for taking my question.  My question goes to something that came out in an interview with Dr. Carolyn Bridges the other day.  She really indicated that the time lapse between an outbreak of some kind and confirmation is crucial, trying to narrow that time lapse.  Is CDC or the U.S. government considering giving countries like Mexico more full scale labs is so we can shorten and narrow that time lag, so to speak?  Because it seems like during that time lag people are highly contagious but nonsymptomatic and each day that goes by is crucial.  Thank you for taking my question. 

Anne Schuchat: You know, our international strategy has been vital to our pandemic preparedness effort.  The CDC has been working with the world health organization in a number of ministries of health around the world to strengthen their pandemic preparedness and in some of the world to strengthen their efforts at being ready for avian influenza.  This pandemic preparedness efforts involved investments in laboratory capacity, investments in epidemiologic capacity, rapid response teams to be able to respond to clusters of unusual illness, and we think those are really vitally important in shortening the time between when a problem happens and when it's of investigative and responded to, so that the laboratory capacity for influenza is just central to the recognition of a new virus, and it is a big part of our investment.  As we've said on previous calls, one of the issues that has been part of our partnership with Mexico has been strengthening their laboratory capacity for this particular new virus, so that they'd be able to detect this strain in the background of all the other respiratory viruses that are out there.  We have done in the context of this response, of course, we shift the new reagent, the test kits to dozens of countries around the world, and we've made this a part of the WHO partnership really, so I think your question is spot-on, because whether it's this H1N1 or virus or something else, having strong laboratory capacity around the world is very important. 

Dave Daigle: Thank you.  Next question, please. 

Operator: Next question is from Delthia Ricks with Newsday, your line is open. 

Delthia Ricks: Thank you for taking my question.  I'd like to know if you can give us a sense of what the level of concern is now that this virus is in circulation, along with, in some parts of the world, the endemic prevalence of H5N1. 

Anne Schuchat: You know, this is a very unusual circumstance we have right now, to have a new H1N1 strain that's very easily transmittable, that is spreading in our continent and has arrived in many others, and then to have parts of the world where the animal outbreak or enzootic of H5N1 is occurring.  He we know the H5N1 strain can be very virulent although right now it has not become officially transmitted human-to-human.  One of the big challenges with the influenza viruses is the way that they change, the way that they combine and their prevalence in the number of different species.  So we do think this is unusual and difficult circumstance to have circulation of this new H1N1, the regular seasonal flu viruses and in certain countries, the H5N1.  This is why it's so important for countries to have strong capacities to deal with influenza and also why it's very important to focus on what happens at the interface between people and animals, and these are areas of attention that we're paid, that we're investing resources into with a lot of other partners. 

Dave Daigle: Thank you.  Next question, please. 

Operator: Next question Andy Pollack with the New York Times, your line is open. 

Andy Pollack: Yes, thank you, good morning.  Pardon me, I haven't been paying that much attention over the last couple of weeks of the epidemiology but is there any sense that the number of new cases is leveling off, diminishing or is it kind of accelerating? 

Anne Schuchat: yes, that's --

Andy Pollack: I was wondering if you might explain the concept of the epidemic threshold.  I know we're not at it but what exactly defines the epidemic threshold? 

Anne Schuchat: Great, okay.  You know, I think some of you have seen the what we call epidemic curves, cases by day of onset or cases by day of report, our MMWRs this past week showed epidemic curves for the U.S. and Mexico, and I think that the New England Journal article earlier this week also showed an epidemic curve for the U.S.  It's important to say that those curves do not incorporate a lag time that additional cases may be happening, and are not yet showing on the curves, so we think that the trends that you see, a big peak and then a decline are not an accurate assessment of the ongoing occurrence of disease.  We do think here in the U.S. it's possible that increased cases are occurring, and it's too soon for us to say whether its some community’s things are getting better.  Our indicators suggest there are things still be accelerating, we're still seeing an increase in cases.  The issue in Mexico, there's a little bit more data to suggest they may be in some parts of the country seeing a decline, in other parts perhaps not yet, but so I would say that we don't think there's a drop in occurrence of this illness here in the U.S., and that's why we're trying to use some of our routine seasonal flu systems to way things are going.  The epidemic threshold, that's an issue where we look year and year, you know, many years in a row, we average how much disease should you have on a particular week, compared with historical baseline, and there's a range that is within what we usually see, and when we talk about an epidemic threshold with seasonal influenza, it means we've gone outside those bounds.  This can happen in a regular flu season.  It's a way where we can estimate week-to-week, you know, this looks like a little bit worse regular flu season than what we've had in the past five or ten years.  It doesn't really relate to the pandemic concept.  It's a term we use for understanding seasonal flu.  If you look back at the 2003-2004 season we think of that as a pretty severe season.  That exceeded the epidemic threshold during many of the season. 

Dave Daigle:  I think that was our last question.  I remind everybody we're not planning a briefing for Sunday.  Our next scheduled or planned briefing will be Monday, and we'll announce that time or send out a media advisory Monday morning.  We want to thank everybody for joining us today and wish everybody a happy Mother's Day. 

Operator: This concludes today's conference.  We thank you for your participation.  At this time, you may disconnect your lines. 

End

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