CDC Telebriefing on Investigation of Human Cases of H1N1 Flu

Anne Schuchat: Good afternoon, everyone.

The H1N1 virus continues to circulate in the United States and in many other countries. As you know the World Health Assembly has been meeting this week in Geneva and the Department of Health and Human Services are there. I understand there′s been excellent global cooperation to understand the virus and to take productive measures. There′s a reminder really in the meeting about the role of personal responsibility -- national responsibility and personal responsibility in addressing this issue. In terms of the personal responsibility we remind you that people who have flu-like illness shouldn′t be traveling. If your kids are ill, you should keep them home. If you′re ill, you should stay home from work. Those are simple necessary messages, but something we think is necessary at this point with the virus widely circulating.

The virus is still circulating here in the U.S. People are continuing to become ill, are continuing to be hospitalized, and unfortunately we do have some deaths. Twenty-two states are spreading activity. As many of you have heard that New York City and a few other places have been closing other places like schools as a result of a large number of children having influenza-like symptoms. Those steps that New York City are taking are consistent with the guidance we′ve issued around schools. There′s a need for localized responses, and when absentee rates are high or our staff are ill, it′s appropriate to close schools if they′re really not able to function.

I want to highlight two areas of particular interest. I want to focus a little more on protecting children during an outbreak, plus a series of hospitalized patients that were reviewed from California. Outbreaks of schools have been a big feature of this H1N1 virus in terms of our population experience. We are seeing outbreaks in a number of schools at a very late point in the season, very different from the picture with seasonal influenza where we sometimes have school outbreaks, but they aren′t this late in the year. It′s understandable that parents are frustrated and are looking for ways to protect their children from flu and other infectious diseases. As we know from seasonal influenza, aside from closing school for a very extended period of time, there′s really no approach that′s going to completely stop or prevent transmission of flu in a school setting. We take that kind of intervention very seriously. We typically would reserve that kind of thing for a very severe influenza-type of virus. If the school is closed for a suspended period of time, children are still susceptible to flu if they interact with other people, some of whom might be contagious even though they don′t have visible symptoms. We′re working together to strike a balance between measures that may have a balance between slowing transmission and those that create other problems. Seasonal influenza illness rates are highest in school-aged children. That′s a reason that we recommend seasonal flu vaccines for children in the ages -- all the way up to age 18. The seasonal influenza vaccine recommendations were issued in the past couple of years, and those have been recommended in order to reduce school absenteeism and to keep kids healthy and in school where they can learn.

We also have been recommending seasonal flu vaccines for children with chronic health problems like asthma and diabetes, who are at higher risk of developing serious complications from the seasonal flu. But thankfully, serious complications from seasonal influenza are rare in school-aged children. When it comes to the H1N1 virus, so far it seems like the largest number of our novel H1N1 confirmed and probable cases are occurring in people from the ages of 5 to 24, so many of them would be school-aged children. We don′t have any deaths reported in people of this age group at this time. But we would not be surprised to see serious hospitalizations and deaths occurring in people of this age group. I think we need to be prepared for that.

But stepping back and looking really at the big picture and what we can do about it, I do think that public health schools and parents are able to cope with this. We experience the kind of challenge that we′re seeing right now during seasonal flu season. While we don′t have perfect measures, we are able to manage. It′s important that children and school staff who are ill stay home, and we′re recommending that they do so for seven days in terms of our current guidance. We may be changing guidance in the future, but at this point that′s our best recommendation in terms of a time period where people can make sure that they won′t come back to school and infect other people. Unfortunately there′s no approach that guarantees protection from infectious diseases spread like things from influenza viruses. And that′s why we work to develop and use vaccines. Vaccines may ultimately be the best approach to this sort of problem that we′re having, and certainly we think they′re the best approach for the seasonal influenza challenges.

I want to talk a little bit about the MMWR that was issued earlier this morning from California authorities. The authorities in California reported on a series of 30 people who were hospitalized there for the H1N1 virus. They summarized 30 cases as of May 17th, and their detailed descriptions of four cases, which we think illustrate the spectrum of illnesses that we′re seeing among this virus. Even among hospitalized cases there seems to be a range of severity from relatively short hospitalizations to longer, much more complicated hospitalizations. We also have information in that MMWR about underlying conditions that are common among the people who required hospitalizations and information about the chronicle symptoms.

It might be helpful to put in context with some reports that we′ve had from Mexico or from individual physicians who have been caring for patients. About 2/3 of the patients in this hospital series had at least one underlying medical condition that would put them at higher risk for influenza. The most common conditions were chronic lung diseases, conditions associated with depression, chronic heart disease, obesity, and pregnancy was a feature of many of the patients. Pregnancy was -- there were five pregnant women in this series of 30 patients. In terms of the clinical symptoms, nearly all of the hospitalized patients had fever at the time of admission. Only one of the 30 didn′t have fever. Besides fever other common symptoms were cough and shortness of breath, and vomiting was present. That′s unusual for seasonal flu. The preliminary overview of hospitalized patients in this MMWR indicates that although the majority of hospitalized people infected with this new H1N1 virus recovered without complications, certain people did have severe and prolonged disease. None of the patients in this hospitalized series died. There are still some of these patients in the hospital, and so we don′t know whether they′ll make it or not. We do recommend that all hospitalized patients with this novel H1N1 virus be monitored carefully, and we recommend that they be treated with antiviral therapy. Even the ones that come in for care after it′s been more than 48 hours for the onset.

In closing I want to say that we do think this virus is continuing to spread around the country and that our data of to date suggests it′s pretty much all over the United States. While we′re not seeing the seriousness of illness that we saw in those initial reports from Mexico, this virus is capable of causing a range of illness from mild to quite severe or even fatal. This does remain an ongoing health threat. The government is busy focusing on. Public health and clinical providers are busy. But we think there′s a role for everyone in taking action to reduce illness and limit spread. So, all of us do have a shared responsibility in our protective actions. And I would be happy to answer questions now.

Dave Daigle: Thank you. Operator, first question, please.

Operator: Thank you, our first question from Helen Branswell, the Canadian Press, please go ahead.

Helen Branswell: Is anybody looking for, and is anybody finding any evidence of, coinfection with MRSA?

Anne Schuchat: We′re very interested in that question. As you know, the seasonal influenza in children we′ve been tracking pediatric deaths, and we have seen MRSA among seasonal flu cases in children at a higher rate than we had expected. MRSA is a big problem in the United States right now in terms of the community associated resistant staff or its infections. So far as we′ve been looking at the patients with the H1N1 virus, we don′t have evidence of coinfection. Not everybody has been tested for bacterial infections. But among the ones that have been tested, we aren′t seeing an important role for bacterial coinfection, including MRSA. I think this is an important issue for us to continue to follow, whether bacterial co-infections or bacterial pneumonias following the illness are featured. It′s a feature we′re interested in but haven′t seen this turn up yet.

Dave Daigle: Thank you. Next question, operator.

Operator: Next question from JoNel Aleccia at

JoNel Aleccia: You′re talking about the role of personal responsibility today. I have one question. In homes where children have been confirmed to have swine flu, but there are other children, what should the role of the parents be in sending those kids to school, and what should the role of the schools be in allowing them to attend?

Anne Schuchat: You know, at this point for homes that are dealing with a person who is ill with this new virus, we′re recommending that a designated family member be identified who can care for the child or adult who is sick, and that you try to limit contact between that ill person and others in the household. When we look at the household attack rates that we′re seeing in some of our investigations, they′re not that high. It′s not like every single person in the household is coming down with influenza-like illness. So we do think that taking some steps to reduce spread in the household by really just Focusing on one person caring for the sick person may be effective and reduce that even further.

We haven′t recommended that household contacts of children who were ill stay home from school. We have been really trying to strike a balance at this point in the disruption that′s caused by this virus. In terms of health impact. And the disruption that′s caused by a recommendation. That′s the type of measure that′s under discussion always with influenza, and it′s been under discussion in our pandemic planning, but some of the more disruptive steps in terms of the social distancing and community mitigation efforts are usually reserved for the more severe viruses, the ones that look more like that 1918 strain.

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

Operator: Next question from David Brown, the Washington Post.

David Brown: Thank you. I was wondering if you could talk a little bit more about community spread, whether there are any places, any states, and if there are, which ones they are, where there′s sort of true community spread going on through places, through non-school environments, just neighborhoods, et cetera, et cetera, you know. The sort of thing that one sees in bad seasonal outbreaks. Has it gotten that kind of traction yet, and if so, where?

Anne Schuchat: I do think that we′re seeing community spread of this virus. Early on in our response efforts a high proportion of the cases that were being confirmed had history of travel to Mexico. Later on more of them had history of household contact with someone who was ill. I think at this point in addition to the school outbreaks we do believe there′s transmission in the community. That′s one of the reasons that we′re asking people who are ill to stay home and for people who have vulnerabilities, people at high risk for complications from influenza, we′re suggesting that they be careful about attending large gatherings. We know that you can actually spread influenza, including this H1N1 virus before you even have symptoms. So by trying to have the symptomatic people stay home and away from others, we think that′s a good idea. The way we′re tracking what′s going on with influenza around the country right now is a mixture of our surveillance through the influenza-like illness network of providers and through syndromic surveillance systems. Based on those kind of reportings, we think that activity right now is highest in the southwest and in some Midwestern areas, but we actually know that there′s some cities that are having a bit more disease than the whole state. On our website you can find something called flu view that has a map showing whether states are designated by their experts to be having widespread activity or regional activity or local activity. Widespread activity means more than half of the regions in the state are having influenza-like illness above the baseline rate. So even in some states that aren′t having widespread activity, we know from some of the syndromic surveillance systems that disease is quite high in certain cities. So at the state level we think activity is high nest the southwest and the midwest, and then through the media reporting there are probably a number of cities having more than expected disease.

Dave Daigle: Next question, operator.

Operator: Next question from Emma Hitt, MedScape. Please go ahead.

Emma Hitt: Thanks for taking my call. It came out last night that the woman who was pregnant in Texas and died from H1N1 in Texas had no other medical conditions apparently. She was perfectly healthy and died. So is pregnancy considered an underlying medical condition?

Anne Schuchat: Of course, pregnancy a great thing, and it′s not a disease. On the other hand, pregnancy can increase your risk of certain medical problems. Pregnancy is a risk factor for worse complications from influenza. There are probably multiple mechanisms by which that occurs. There is some suppression that occurs during pregnancy. There may be also a role for the mechanical affect of pregnancy in decreasing the lung capacity. You know, when you′re very pregnant your lungs don′t expand as well. Maybe you′re not easily able to handle a lung infection. The effect of pregnancy is well known for a number of infectious diseases. For many years we recommend that all pregnant women receive seasonal flu vaccines to reduce their chance of complications. In some of the reports so far, the hospital series and earlier MMWR that we did about pregnancy, we reminded people about that seasonal flu vaccine recommendation, but we also saw in some of the case reports it was not just a risk to the mother. There were sometimes occurrences of complications of pregnancy, like pre-term labor. So we really think influenza can be much worse in pregnancy, and that′s something that we′re attending to. We′ve issued guidance for clinicians to say that it′s important to treat with antiviral drugs. We think at this point pregnancy is a risk factor for worsening complications of H1N1.

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

Operator: Next question from Richard Knox, National Public Radio.

Richard Knox: Is there evidence you know of that the new H1N1 is outcompeting seasonal flu viruses in some place? Are they circulating in the same schools with these new viruses? And if evidence does emerge that the new virus is overtaking seasonal viruses, what implications would that have for planning, need for a vaccine or perhaps a signal of increasing fitness of the new virus?

Anne Schuchat: This is a really important issue. We know that regular seasonal influenza viruses are continuing to circulate right now. Of course, we think we′re doing a lot more testing and looking a bit harder for them. So we′re seeing more of them than we would usually see at this time of year. On the other hand, the non novel H1N1 viruses, the seasonal flu viruses are no longer the majority of cases of viral testing that we′re seeing. At this point for the period since -- let me just see how this works. Well, we think that it may be as much as half or even more of the viruses that we′re testing right now that are this new H1N1 virus or that couldn′t be subtyped in. We think that are essentially the same thing. So the seasonal flu viruses continue to circulate. The particular risk here, especially in planning, looking towards the fall, is that co-circulation of this new virus together with our seasonal strain might put us at risk for there to be a reassortment event. In particular we′re concerned that the seasonal H1N1 virus right now is resistant, but this new H1N1 strain is susceptible. If those two strains reassorted and we got a new strain that was a combination of those two, we would hate to see this novel strain essentially become resistant through that mechanism. The issue of individual schools or localities is a little harder for me to answer based on the data that I have. I′m aware that we have seen in cities with active school outbreaks, they′re still finding patients with influenza-B. But in terms of the same school or household, I don′t have that type of day that.

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

Operator: Next question from Steve Steinberg, USA Today.

Steve Steinberg: Would you mind talking a little bit more about the course of illness based on the California data, but others. Are people coming in with extremely high fevers? You know, what sorts of -- what sorts of symptoms are you seeing? I know there′s the usual range. But if you could help pin down what this illness looks like, that would be helpful.

Anne Schuchat: Yes, the presenting symptoms do include fever in most people. But sometimes it′s not a very high fever. It ranges from a low-grade fever to quite high. We do see pneumonia or x-ray findings in a number of the patients. 60% of the hospitalized reports had infiltrates on an x-ray. Intensive care units emission was required by 20% of the patients in that hospital series, and mechanical ventilation, really a sign that it′s a very severe respiratory illness was required in 13% of the hospitalized patients. So this -- while some people came in with relatively minor dehydration or an exacerbation of asthma, others had a stress syndrome. The vast majority of those who didn′t have underlying medical conditions or pregnancy had pretty short hospitalizations that were not complicated. Some of those with the medical conditions had prolonged and difficult hospitalizations.

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

Operator: Next question is from Delthia Ricks from Newsday.

Delthia Ricks: I would like to know if any of the H1N1 isolates carry a factor that would account for what you′re seeing in symptoms?

Anne Schuchat: What has been looked at so far in the laboratory through the genetic sequencing that has been done is to try to see if the marker from the 1918 campaign or the the bird flu. We haven′t seen those markers or signals. On the other hand, it′s probably multi-factorial. I think the researchers both here and around the world who are looking at the sequences of the viruss are studying them to understand whether there may be new things. On the other hand we know with even seasonal influenza virus strains, we see a range of clinical illness. Every year between 50 and 100 children die from seasonal influenza. So viruses, even the ones that cause minor illness in most people can actually cause quite severe disease without the special markers found in 1918.

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

Operator: Next question from Kate Traynor, AJHP.

Kate Traynor: Thanks so much for taking my question. The MMWR report on the California patients mentioned obesity as a risk factor in several of the people who were hospitalized. I know obesity by itself isn′t specifically listed as a risk factor for either seasonal influenza vaccination or using ANTIVIRALS. Should physicians be thinking about giving these patients ANTIVIRAL medications if they seem to have the H1N1 flu?

Anne Schuchat: We were surprised by the frequency of obesity among the severe cases that we′ve been tracking. I do think it′s an important result. The question of whether people with obesity need to be treated differently in terms of ANTIVIRAL treatment or seasonal flu vaccinations is one we′re looking into right. If there truly is an increased risk of severe complications on obese patients, it would be important to take steps to attend to that. One unfortunate statistic right now is that the U.S. is experiencing an epidemic of obesity. We had much higher rates of obesity in the U.S. than we had 10 or 20 years ago. Both in children and adults. So it′s hard for us to say at this point to say whether the number of patients with reported obesity is significantly higher than we would expect. It was a bit surprising on first glimpse. A lot of theorys people are entertaining now. Some people with morbid obesity have a syndrome where they have fairly severe respiratory compromised just based on the extra weight they′re carrying on their chest. We know chronic lung disease is a risk factor for influenza complications and the need for vaccination. So we′re speculating about whether that′s what′s going on in this circumstance or whether we haven′t analyzed things well enough to know if it′s more than we would expect by chance alone.

Dave Daigle: Operator, we can take two more questions, please.

Operator: Our next question from Alyah Khan, Inside Washington Publishers.

Alyah Khan: Thanks for taking my call. My questions relate to health care workers. My first question is if there′s any number you can give of confirmed cases of health care workers who have been infected with the H1N1 virus. The second part of my question was there′s been concern express ed that local and health state departments aren′t conforming to the guidelines in terms of protecting workers. Is the CDC or any other agency taking steps to address gaps in protecting health care workers, and if not, are the state and local health departments, are they required to follow the CDC guidance?

Anne Schuchat: Health care workers are vital to the response to influence as well as other medical conditions. They′re really at the front line of caring for the ill. Protecting health care workers is very important to us. We′ve issued interim guidance for protecting workers against this H1N1 strain based on the lack of information about all the different ways this new strain can spread. Our recommendations for the novel H1N1 virus are a bit more strict than our recommendations for seasonal influenza in terms of respiratory droplet protection versus additional steps that are taken for avoiding airborne exposure or small droplets of transmission. I would say if guidance for health care workers is something that we continually evaluate. Whether it′s strong enough or too strong is an important question of great concern I think to a number of organizations and individuals. We are investigating health care workers. I don′t have today′s latest statistics. I was just looking for them while I was talking to you about how many health care workers have been reported to have the new virus. We have a couple of investigations ongoing to look at this. Have the workers who had the virus been exposed in the community or at home or through travel, for instance? Or is it possible they got this on the job? In some of our investigations we′re finding there are a lot of exposures in the community and that the illness isn′t necessarily from the health care environment. So I think the issue of health care worker is very important in this kind of thing. We′re continuing to reevaluate our guidance.

Dave Daigle: Last question, please, operator.

Operator: Our final question from Sylvia Garduno, Reforma Newspaper.

Sylvia Garduno: Hi, hello. Thanks for taking my question. It is regarding with the released of hospitalized patients with influenza. 17 of the patients were Hispanic. I don′t have if you have any other reference about if this illness is affecting Hispanics more than other ethnic groups in the United States or what is happening. What can you say about this information? Thank you.

Anne Schuchat: Thank you for that question. I don′t have the statistics nationally about the racial or ethnic breakdown of the cases. The California experience which was reported in the MMWR describes people who were detected with the illness relatively early in the course of this outbreak. The California health department initiated active surveillance for hospitalized patients very early. Because they were the state that had the first cases of this condition. They initiated their act of surveillance April 20th, before we went to a national alert. And so the frequency of Hispanics in that series might be quite different than the rest of the U.S., both because it′s early reports where we think many people had exposure to Mexico. In California it′s very common to have exposure to Mexico. The Hispanic population is much greater than the rest of the country. At this point I don′t have the national statistics. I′m not sure we can make a lot of conclusions on that particular report.

Dave Daigle: This concludes our briefing at this time. Thanks for joining us, everyone.