|Rhiza Labs FluTracker Forum
|76% of Newly Tested H3N2 in US Are Low Reactors
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|Author:||niman [ Fri Dec 05, 2014 5:18 pm ]|
|Post subject:||76% of Newly Tested H3N2 in US Are Low Reactors|
Yesterday the CDC held a presser warning about US H3N2 mismatch in the current vaccine this season and noted that about 50% were low reactors. However, the total for the season is a trailing indicator. In the current week 48 FluView, 29 new samples were tested, and 22 were low reactors (76%) signaling the steady decline in the number of H3N2 isolates that match the 2014/2015 vaccine H3N2 target (which has already been changed for the southern hemisphere).
|Author:||niman [ Fri Dec 05, 2014 5:41 pm ]|
|Post subject:||Re: 76% of Newly Tested H3N2 in US Are Low Reactors|
OPERATOR: Welcome and thank you for standing by. At this time all participants are in listen and only mode. During the question and answer session section, please press star 1 on your phone. Today's conference is being recorded. If you have any objections, you may disconnect at this time. Now I'd like to turn today's meeting to Tom Skinner, Senior Public Affairs Officer, CDC. You may begin.
TOM SKINNER: Hi, Rebecca, and thank you, all, for joining us today for this telebriefing on an update on this year's flu season as well as discussions about health advisories CDC has put out regarding the potential use of antivirals this coming flu season. With us today is the director of the CDC, Dr. Tom Frieden, who will provide some opening remarks, and then we'll get to your questions. Dr. Frieden.
TOM FRIEDEN: Hello everyone and good morning. Thanks very much for joining us. We've got some new information on influenza for this year. The flu season is beginning and we are seeing some things that are concerning and that led us to issue a health advisory to clinicians across the country. One thing to understand about flu always is that it is unpredictable. Every season is different with different flu viruses spreading and causing illness. So far, this season influenza A, which is called H3N2 viruses have been detected most frequently and in almost all states. We know that in seasons when H3 viruses predominant, we tend to have seasons that are the worst flu years, with more hospitalizations from flu and more deaths from the flu. Unfortunately, about half of the H3N2 viruses that we've analyzed this season are different from the H3N2 virus that's included in this year's flu vaccine. They are different enough that we're concerned that protection from vaccinations against these drifted H3N2 viruses may be lower than we usually see. Most of the other viruses identified are the same as the viruses covered by the vaccine. We continue to recommend flu vaccine as the single best way to protect yourself against the flu. Vaccine will protect against the strands that are covered in the vaccine and may have some effectiveness against the drifted strain. While vaccination is still important, I want to emphasize a second tool to fight the flu and the complications that flu causes, and that is antiviral medications. Antivirals are not a substitute for vaccinations. Vaccinations prevent flu, but antivirals are an important second line of defense to treat the flu. This year, treatment with antiviral drugs is especially important, particularly for people who are at high risk of serious flu complications or for people who are very sick with flu. It's especially important to get antiviral medicines quickly if you have flu. They work best when you start them within two days of the beginning of flu symptoms, and we strongly recommend that if doctors suspect the flu in someone who may be severely ill from the flu, they don't wait for the results of a flu test before starting antivirals. I'll say a little more about this, and then I'll answer questions along with Dr. Joe Bresee from the influenza division. influenza activity has increased slightly in parts of the U.S. and surveillance data indicates that influenza A, H3N2 viruses have predominated so far with lower levels of detection of influenza B viruses and very few of the H1N1 viruses we've seen a few years ago. During the week ending November 22nd, 91 percent of the approximately 1,200 flu positive tests reported to the CDC were influenza A, and 9 percent were influenza B viruses. As I noted before, of the influenza A viruses, nearly all were H3N2, and of those, about half were antigenetically different from the H3N2 component of the 2014 flu vaccine. These changes can signal that the immune response provided by vaccinations won't protect as well for these viruses, and there's a lot of numbers there. Let me go over them again. What we are seeing this year is largely an H3 year, about 90 percent of the viruses we've typed so far are H3. Of the 90 percent, about half are well matched with the vaccine strain, and about half are poorly matched with the vaccine strain, so for the B viruses, about 10 percent, those are well matched. For half of the 90 percent, they are well matched, but for the other half of the 90 percent, they are not well matched, and we may well see less effectiveness, although there also could be some effectiveness against influenza even for the drifted viruses from the vaccine. The drifted viruses were first detected in March of 2014 after -- when it was already too late to include them in this season's vaccine. At that time, the current vaccine component, the one that's covered, the H3 vaccine that's in the strain, that is in the vaccine, was still by far the most common of the H3N2 viruses. These viruses, both the H3 that's well matched and the H3 that's poorly matched are likely to continue to circulate in the U.S. this season, and there is no way to predict with certainty what is going to happen. We have four different strains of flu circulating: The B strain, the h1 strain, the well matched H3 strain, and the poorly matched H3 strain, and only time will tell which of them, if any, will predominate for the following weeks and months of this year's flu season. Flu always has a potential to be serious, but H3N2 viruses tend to be associated with more severe seasons. The rate of hospitalization and death can be twice as high as or more than in flu season when H3 doesn't predominate. People with certain health conditions like asthma, diabetes, heart disease, lung disease, and pregnancy are also at high risk. We're also noting our hospitalizations for the year, and we know, sadly, that so far there have been five pediatric deaths associated with influenza. We've also heard of outbreaks in schools and in nursing homes. During some seasons when the viruses are antigenically drifted, vaccine effectiveness can be lower, but that's not always the case. If we have a severe season with H3N2 virus predominating, getting a vaccine even if it does not provide as good as protection as we hope would be more important than ever and remains the single most important way to protect yourself against the flu. In addition, a vaccination will offer the usual protection of circulating viruses that have not undergone antigenetic draft. We continue to recommend vaccination, because though far from perfect, it still offers us the best chance for prevention. We can't predict what will happen over the entire season. The influenza vaccine is designed to protect from three or four, depending what vaccine you get, different influenza viruses. Any of these could circulate at any time in the season, and if we have a severe season, getting a vaccine that provides partial protection may be more important than ever, so, first, we urge people who have not been vaccinated to get a vaccine now. Companies have already distributed close to 150 billion doses this year. As I mentioned earlier, antiviral treatment is particularly important this year. Many people believe that since flu is a virus, there's no treatment for it. In fact, there are antiviral drugs that work to reduce the severity of influenza. There are two FDA approved drugs recommended for use in the U.S. during this season, Oseltamivir and Zanamivir. Treatment with antiviral drugs works best when they are begun 48 hours of getting sick, but they can still be helpful in some patients when given later in the course of the illness. Treatments with antiviral drugs for influenza can make your illness milder and shorter. It can reduce the likelihood you'll end up in a hospital or in intensive care, and we believe treatment with antiviral drugs can reduce the risk of dying from influenza. Prescription antiviral drugs, however, are greatly under prescribed, particularly for people who are at very high risk of getting the flu. Probably fewer than one in six people who are severely ill with the flu get antiviral drugs. Very important that we do better for people who are severely ill or who could become severely ill with influenza. That's the single most important message of this telebriefing. We need to get the message out that treating early with the drugs makes the difference between a milder illness or a very severe illness. Time is important when it comes to treatment for influenza. Antiviral drugs are even more important when circulating viruses are different from the vaccine virus. This can mean the vaccine is not as effective in this year as it has been in the past, and that cannot only have more people coming down with severe illness, but also crowding emergency departments and hospitals. I also want to remind people of another defense against respiratory viruses like the flu are simple things like staying home if you're sick so that you don't make other people sick. I'll conclude by reiterating we cannot predict what's going to happen in the rest of the flu season. It is possible we could have a season that's more severe than most with more hospitalizations and tragically more deaths. I want to urge anyone who has not got vaccinated to get vaccinated. It's still our best tool to prevent influenza. I've been vaccinated. My family's been vaccinated. If you have not been vaccinated, get vaccinated. Second, to encourage you if you are sick, talk to your doctor promptly about getting antiviral treatment because that can help you get healthy quicker. Third, take everyday actions like covering your cough and staying home if you're sick. With that, I'll stop, and we'll open for questions.
TOM SKINNER: Hi, Rebecca, we're ready for questions, please.
OPERATOR: Thank you, our -- we'll begin the question and answer session. If you have a question please press star 1. Remember to say your name and please unmute your microphone. Our first question comes from Leigh Ann Winick with CBS news, your line is open.
OPERATOR: Okay. Our next question comes from Eben Brown with Fox News Radio. Your line's open.
EBEN BROWN: Thank you, good morning Dr. Frieden, thank you for doing this. Some years back when we had the H1N1 swine flu issue, the manufacturers of the vaccine were willing to come out with separate vaccines for H1N1, if I remember, and to include H1N1 in the general vaccine going forward. Has there been in -- or what's been the result of communications CDC may have had with the drug makers regarding vaccines and getting people vaccinated against this strain, or is it too far in the season to make that happen?
TOM FRIEDEN: Right. During the H1N1 pandemic, by April, we had the vaccine and could begin the production. Here, we only saw this drifted strain become common in September. By which time the vaccine was already out. Even with the newer vaccine technology, a cell based production; it takes four months to make the vaccine. Essentially, the flu change was too late for the vaccines to be changed.
TOM SKINNER: Next question, Rebecca?
OPERATOR: Our next question comes from Liz Szabo with USA today. Your line's open.
LIZ SZABO: Thanks. I've seen some data showing that there's not a correlation to match the vaccine and the virus and its effectiveness. Do we need a better measure of the vaccine effectiveness?
TOM FRIEDEN: Each year, we do studies to measure the effectiveness of the vaccine, and we find variability in how effective the vaccine is. They are not easy studies to do because we don't always have the contracting of each patient who has flu vaccine, but the bottom line is that the flu vaccine is our best tool for prevention that the effectiveness of the flu vaccine does tend to vary year to year, and that the drifts that we're seeing may indicate that it may be less effective this year, and that's why we think that it is particularly important that people who are very sick, who are at risk of becoming very sick get antiviral drugs, Tamiflu, promptly. I'd like to turn the question over for a more in-depth answer to Dr. Joe Bresee.
JOE BRESEE: Yes this is Dr. Joe Bresee. I agree with what Dr. Frieden said. It's clear that the laboratory tests we're using to understand how closely related this virus is to the vaccine virus is are good, but they're imperfect markers of how well the vaccine will function in the field. We'll know that soon. We do study's every year in the field to measure the real life effectiveness of how well these vaccines work in the field. We'll have that data sometime in the middle of the season. We'll know the answer to this. You're right to the extent that these aren't perfect markers of what to expect in terms of how well the vaccine will work, but they are related to how well the vaccine worked. As a note of caution, once we saw the drifted strains, the strains that look somewhat different than the vaccine strains, we wanted to make sure that people knew and make sure that people knew the tools like antivirals they had to medicate the disease and flu.
TOM SKINNER: Next question, Rebecca
OPERATOR: Our next question is from Dan Childs with ABC news. The line is open.
DAN CHILDS: Thank you very much for taking my question. With regard to the antivirals, we've seen in past years that sometimes stocks have been somewhat depleted that there have not been necessarily enough. Will they be sufficient this year? What, if anything, is the CDC doing now to ramp up production?
JOE BRESEE: Yeah, that's a great question. This is Joe Bresee again. We're not aware of any shortages now, and we expect to have enough antivirals to meet the demand this year. Occasionally because the pediatric formulation suspensions are in short supply, we may have shortages in that and sometimes do, but we have ways to get around that by taking the capsules and making a formulation for children. And there are directions for that on the CDC website.
TOM SKINNER: Next question, Rebecca.
OPERATOR: Thank you. Our next question is from Caitlin McCabe with the Wall Street Journal.
CAITLIN MCCABE: Hi, thank you. I had a question. Can you give an update about the shortage in production delays that the vaccine itself that was a problem earlier this year?
TOM FRIEDEN: We -- other than spot shortages in individual areas that were short lived in the season, we have not heard. For wide spread shortages, we think there's ample vaccine out there. 145 million doses have been distributed by manufacturers, and that should be sufficient for the demand.
JOE BRESEE: That's exactly right. I have nothing to add.
TOM SKINNER: Next question, Rebecca?
OPERATOR: We have Mike Stobbe with the Associated Press. Your line is open.
MIKE STOBBE: Hi, thank you for taking the question. Couple questions. First, clarification, you talked about an antigenetic drift, the H3N2 that's 52 percent of the samples showing positive for antigenetic drift. Are you talking about the type of H3N2 that has been seen before, but just happened to be the one that's most common at the moment, or is this a new type of H3N2 not seen before? Also, can you they more about one in six severely ill people get antivirals, why is it that low, do you think, and I'm sorry, one more. In October, there was a presentation of information that the H1N1 flu mist may not be effective in children. You talked about the flu vaccine being well matched to the other trains, but there's that information there about the flu mist may not be as effective against H1N1 this year. Can you incorporate that in the overview?
TOM FRIEDEN: Thanks. First, the drifted strains, and those of you who cover flu regularly know, we talk about shift and drift. Shift being bigger changes and drift being smaller changes. This is an example of drift. In March, I believe the first three strains drifted in this way where identified and it was not until over the summer, then in September that we saw them in significant numbers. So this is not something that's been around before. It is as we see that unpredictability of influenza with new strains coming up, possibly as a result of vaccinations where they are escaping the immunity that's being developed. In terms of antiviral use, there are many reasons why it's not used as commonly as it should be used. One of the issues is a misconception you have to test for it first. In fact, many of the tests can have some false negatives, and we strongly encourage doctors not to wait for a test, but to treat if it's indicated to treat. I think it is just a pattern of prescribing, but it's not familiar to doctors to use antivirals for influenza. The benefit is not as marked as the benefit for some bacterial infections where you see a very gratifying resolution of an infection that otherwise would have progressed to show the benefit. It's essentially about a day less of severe illness, and that results in a reduced risk in hospitalization and likely of death as well. In terms of flu mist, we believe that flu mist is likely to be effective against the matched strain this year. We continue to recommend it. It was, as you note, a -- an analysis of one's subgroup that suggested that it may have been less effective against h1 last year. H1 is not prominent this year, but we're working closely with researchers around the country as well as with the companies to try to understand whether that's, in fact, what happened, and if so, why? Dr. Bresee, would you like to add to that?
JOE BRESEE: In response to the investigation into why the live attenuated influenza vaccine, the nasal spray vaccine, worked less well against the h1 than we expected. There has been lots of evaluation, but for now, the CDC policy remains the same that the children 2 to 8 years old should receive the nasal spray if available when they go to the doctor. We want to make sure that when kids show up to the doctor and the nasal spray is not available, get the shot, get vaccinated with the vaccine, don't try to come back for the nasal spray when it's available.
TOM FRIEDEN: One other reason why we see low rates in treatments is that unfortunately, people wait to see the doctor. If you're high risk, if you have lung disease, heart disease, diabetes, and you get symptoms, contact the doctor right away. I will say many health care systems increased the availability of antivirals using nurse call lines as a way of patients calling in, having them come into the office, getting assessed over the phone, and then if it is appropriate, getting prescribed and able to pick up antiviral medication that may keep them out of the hospitals.
TOM SKINNER: Next question, Rebecca.
OPERATOR: Our next question comes from Julie Steenhuysen with Reuters. Your line is open.
JULIE STEENHUYSEN: Yeah, hi, thanks for taking my call. Dr. Frieden, I'm curious, I know that you're recommending antivirals and, of course, you want to treat every weapon you have to treat the flu, but I'm wondering what you think about the Cochrane review study -- I think it was in April that suggested antivirals are not very effective when it comes to preventing hospitalizations from flu. How do you balance that? Thanks.
TOM FRIEDEN: We looked in detail at the data on Oseltamivir. We looked at published and unpublished data. We looked at the full data set, and it is the opinion of the CDC scientists that the evidence is strong. That Oseltamivir given early in the course of illness will reduce the length of illness by about a day. It is not a miracle drug, but we believe it is an effective drug, and we think there's some methodological issues with that review related to what are some of the outcomes looked at, what are some of the sample sizes, what was the data included? There was some concern that not all data had been shared by the company. We have looked at a broad swath of data available, and we see a consistency of the data that does indicate to us that there is some ethicacy of the drugs. Again, they are not perfect. We wish we had better drugs. We wish we had a better vaccine. Right now, the best way to protect yourself against the flu is to get a vaccine. The best way to reduce the length of your illness is antiviral drugs, and the best way to protect other peoples is not to go out when you're sick.
TOM SKINNER: Next question, Rebecca.
OPERATOR: Next question, Donna Young, Script news.
DONNA YOUNG: Thank you for taking my question. I was wondering why if you started seeing this significantly in September, you waited until December to make the information available? Also, are you concerned that because you put out this notice last night or late yesterday, that headlines got ahead of your message today? Thank you.
TOM FRIEDEN: We have been providing this information all along through the mmwr and through a slew of you. Dr. Bresee will go into more details.
JOE BRESEE: Yes, that's a good question. We've been tracking it closely since it emerged in March. In September, we published the mmwr wrapping up the summer season, and we mentioned predominantly in that MMWR that we're seeing it during that May to September period. Globally it accounted for 50 percent of the H3 viruses that were looked at globally. There were not that many viruses still at the time in the United States, and it's not really until now when we're starting to see more flu activity in the United States, that we're seeing a lot of the viruses. So up until now, there's been so little activity it was hard to say that the virus was going to be a public health concern or not. I think now with the increasing cases of flu and that this virus is maintaining a presence and maintaining prevalence in the United States, we felt it necessary to come out and talk about it a little bit because we think antivirals provide a fantastic way to mitigate the disease you might get.
TOM SKINNER: Next question, Rebecca.
OPERATOR: Next question from Robert Lowes from Medscape Medical News. Your line is open.
ROBERT LOWES: Yes, thank you for taking my question. I have two. One, for the 2013-2014 flu season, do you have any figure for the effectiveness of the seasonal flu vaccine, do you have a percentage level of effectiveness, and, second, there was an mmwr report recently talking about an outbreak of this H3 flu virus aboard a naval ship, and 99 percent of the sailors have been vaccinated, but one-fourth of them came down with the flu. Is this an example of the problem with the vaccine being unable to cope very well with the drifted H3 virus strain?
JOE BRESEE: Yes, good questions, thank you. So, first, the effectiveness question. We presented data a couple times over the summer that looked at last year's vaccines and how effective it was, and, as usual, it was 50 to 55 percent effective overall in the United States last year, the vaccine was. We'll come out next week as a teaser, we'll come out next week with an mmwr that describes what health impact the vaccination program for last year had in terms of averted cases, hospitalizations, and clinic visits. Pay attention to the space next week. The outbreak you're talking about in the naval ship last year was actually an H3 outbreak, as you said; it was not this H3 virus, but a previous H3 virus, the one that was predominant last year. We do see outbreak viruses like influenza on cruise ships, on ships with closed spaces because so many people are crammed together in close contact. It's easy to spread viruses, even among the highly vaccinated population. That was a useful investigation highlighting the importance of flu and naval ships and cruise ships and the importance of using antivirals again in context like that.
TOM SKINNER: Next question, Rebecca.
OPERATOR: Next question, Michael Smith, Medpage today, your line's open.
MICHAEL SMITH: Yes, thank you. Dr. Frieden, you said there were, that there have already been five pediatric deaths. Two questions, one, put it in context, is that high or low for this time period? Secondly, are they linked with the drifted H3N2, or do you know that information?
TOM FRIEDEN: I'll let the doctor give more details, but each year of the pediatric deaths, we generally find that about 90 percent of the kids had not been vaccinated, so we really do emphasize vaccination as the most important preventative tool for influenza in terms of the five cases, Dr. Bresee will give more information.
JOE BRESEE: The five children known to die from the flu so far this year, four were infected with influenza A, three of those we've confirmed are H3 viruses. One who died with an influenza B virus. We don't know if the H3N2 viruses the three children had when they died was this virus, the drifted virus, or the other virus.
TOM FRIEDEN: So, I'll just thank everyone for joining us. Let me wrap up by emphasizing that flu is unpredictable, but what we've seen so far this year is concerning for two reasons. First, that it is likely to be, so far, an H3 predominant season, but that could change. An H3 predominant season tends to have more hospitalizations and more deaths, and, second, that so far about half of the H3 strains have been drifted and there may be a lower effectiveness of the vaccine. It still is essential to get vaccinated. Vaccines are the most effective way of preventing influenza, but we are especially recommending this year that people are severely ill or people who may become severely ill because you have diabetes, lung disease, heart disease, asthma, or pregnancy, see your doctor promptly if you have cough, fever, symptoms of flu, and ask about prompt treatment with antiviral drugs. So thank you very much for joining us.
TOM SKINNER: Thank you, this concludes our call. Reporters needing additional information can call the CDC Press office at 404-629-3286. Thank you.
OPERATOR: Thank you, all, for attending today's conference. You may now disconnect.
http://www.cdc.gov/media/releases/2014/ ... eason.html
|Author:||niman [ Fri Dec 05, 2014 5:43 pm ]|
|Post subject:||Re: 76% of Newly Tested H3N2 in US Are Low Reactors|
CDC Health Advisory Regarding the Potential for Circulation of Drifted Influenza A (H3N2) Viruses
Health Alert Network logo.
This is an official
CDC HEALTH ADVISORY
Distributed via the CDC Health Alert Network
December 3, 2014, 16:00 ET (4:00PM ET)
CDC is reminding clinicians of the benefits of influenza antiviral medications and urging continued influenza vaccination of unvaccinated patients this influenza season.
Influenza activity is currently low in the United States as a whole, but is increasing in some parts of the country. This season, influenza A (H3N2) viruses have been reported most frequently and have been detected in almost all states.
During past seasons when influenza A (H3N2) viruses have predominated, higher overall and age-specific hospitalization rates and more mortality have been observed, especially among older people, very young children, and persons with certain chronic medical conditions compared with seasons during which influenza A (H1N1) or influenza B viruses have predominated.
Influenza viral characterization data indicates that 48% of the influenza A (H3N2) viruses collected and analyzed in the United States from October 1 through November 22, 2014 were antigenically "like" the 2014-2015 influenza A (H3N2) vaccine component, but that 52% were antigenically different (drifted) from the H3N2 vaccine virus. In past seasons during which predominant circulating influenza viruses have been antigenically drifted, decreased vaccine effectiveness has been observed. However, vaccination has been found to provide some protection against drifted viruses. Though reduced, this cross-protection might reduce the likelihood of severe outcomes such as hospitalization and death. In addition, vaccination will offer protection against circulating influenza strains that have not undergone significant antigenic drift from the vaccine viruses (such as influenza A (H1N1) and B viruses).
Because of the detection of these drifted influenza A (H3N2) viruses, this CDC Health Advisory is being issued to re-emphasize the importance of the use of neuraminidase inhibitor antiviral medications when indicated for treatment and prevention of influenza, as an adjunct to vaccination.
The two prescription antiviral medications recommended for treatment or prevention of influenza are oseltamivir (Tamiflu®) and zanamivir (Relenza®). Evidence from past influenza seasons and the 2009 H1N1 pandemic has shown that treatment with neuraminidase inhibitors has clinical and public health benefit in reducing severe outcomes of influenza and, when indicated, should be initiated as soon as possible after illness onset. Clinical trials and observational data show that early antiviral treatment can:
shorten the duration of fever and illness symptoms;
reduce the risk of complications from influenza (e.g., otitis media in young children and pneumonia requiring antibiotics in adults); and
reduce the risk of death among hospitalized patients.
As of November 22, influenza activity has increased slightly in most parts of the United States. Surveillance data indicate that influenza A (H3N2) viruses have predominated so far, with lower levels of detection of influenza B viruses and even less detection of H1N1 viruses. During the week ending November 22, 1,123 (91.4%) of the 1,228 influenza-positive tests reported to CDC were influenza A viruses and 105 (8.6%) were influenza B viruses. Of the 85 influenza A (H3N2) viruses collected by U.S. laboratories and antigenically or genetically characterized at CDC since October 1, 2014, 44 (52%) are significantly different (drifted) from A/Texas/50/2012, the U.S. H3N2 vaccine virus. Drifted H3N2 viruses were first detected in late March 2014, after World Health Organization (WHO) recommendations for the 2014-2015 Northern Hemisphere vaccine had been made in mid-February. At that time, a very small number of these viruses had been found among the thousands of specimens that had been collected and tested, but these viruses have become more predominant over time. Most of the drifted H3N2 viruses are A/Switzerland/9715293/2013 viruses, which is the H3N2 virus selected for the 2015 Southern Hemisphere influenza vaccine. These drifted viruses will likely continue to circulate in the United States throughout the season. All influenza viruses tested for resistance to neuraminidase inhibitors this season have shown susceptibility to both oseltamivir and zanamivir. Given the likelihood that the drifted influenza A (H3N2) viruses will continue to circulate this season, CDC is issuing the following recommendations to remind clinicians of CDC’s guidance for the use of influenza antiviral medications.
Recommendations for Health Care Providers
Clinicians should encourage all patients 6 months and older who have not yet received an influenza vaccine this season to be vaccinated against influenza. There are several influenza vaccine options for the 2014-15 influenza season (see http://www.cdc.gov/flu/protect/vaccine/vaccines.htm).
Clinicians should encourage all persons with influenza-like illness who are at high risk for influenza complications (see list below) to seek care promptly to determine if treatment with influenza antiviral medications is warranted.
Summary of CDC Recommendations for Influenza Antiviral Medications for the 2014-2015 Season:
Clinicians should continue to vaccinate patients who have not yet received influenza vaccine this season.
Clinical benefit is greatest when antiviral treatment is administered early. When indicated, antiviral treatment should be started as soon as possible after illness onset, ideally within 48 hours of symptom onset. However, antiviral treatment might still have some benefits in patients with severe, complicated, or progressive illness and in hospitalized patients when started after 48 hours of illness onset.
Antiviral treatment with oseltamivir or zanamivir is recommended as early as possible for any patient with confirmed or suspected influenza who:
has severe, complicated, or progressive illness; or
is at higher risk for influenza complications. This list includes:
children aged younger than 2 years;
adults aged 65 years and older;
persons with chronic pulmonary (including asthma), cardiovascular (except hypertension alone), renal, hepatic, hematological (including sickle cell disease), and metabolic disorders (including diabetes mellitus), or neurologic and neurodevelopment conditions (including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy [seizure disorders], stroke, intellectual disability [mental retardation], moderate to severe developmental delay, muscular dystrophy, or spinal cord injury);
persons with immunosuppression, including that caused by medications or by HIV infection;
women who are pregnant or postpartum (within 2 weeks after delivery);
persons aged younger than 19 years who are receiving long-term aspirin therapy;
American Indians/Alaska Natives;
persons who are morbidly obese (i.e., body-mass index is equal to or greater than 40); and
residents of nursing homes and other chronic-care facilities.
Clinical judgment, on the basis of the patient’s disease severity and progression, age, underlying medical conditions, likelihood of influenza, and time since onset of symptoms, is important when making antiviral treatment decisions for high-risk outpatients. Decisions about starting antiviral treatment should not wait for laboratory confirmation of influenza.
Oseltamivir is approved for treatment of influenza in persons aged two weeks and older, and for chemoprophylaxis to prevent influenza in people one year of age and older, while zanamivir is approved for treatment of persons seven years and older and for prevention of influenza in persons five years and older. Because high levels of resistance to adamantane antiviral medications continue to be observed among circulating influenza A viruses, adamantanes (rimantadine and amantadine) are not recommended for treatment or prevention of influenza.
Antiviral treatment also can be considered on the basis of clinical judgment for any previously healthy, symptomatic outpatient who is not considered “high risk” with confirmed or suspected influenza, if treatment can be initiated within 48 hours of illness onset.
Special Considerations for Institutional Settings
Use of antiviral chemoprophylaxis to control outbreaks among high risk persons in institutional settings is recommended. An influenza outbreak is likely when at least two residents are ill within 72 hours, and at least one has laboratory confirmed influenza. When influenza is identified as a cause of a respiratory disease outbreak among nursing home residents, use of antiviral medications for chemoprophylaxis is recommended for residents (regardless of whether they have received influenza vaccination) and for unvaccinated health care personnel. For newly-vaccinated staff, antiviral chemoprophylaxis can be administered up to two weeks (the time needed for antibody development) following influenza vaccination. Chemoprophylaxis may also be considered for all employees, regardless of their influenza vaccination status, if the outbreak is caused by a strain of influenza virus that is not well matched by the vaccine. Antiviral chemoprophylaxis should be administered for a minimum of two weeks, and continue for at least seven days after the last known case was identified.
To reduce the substantial burden of influenza in the United States, CDC continues to recommend a three-pronged approach:
(1) influenza vaccination. The influenza vaccine contains three or four influenza viruses depending on the influenza vaccine—an influenza A (H1N1) virus, an influenza A (H3N2) virus, and one or two influenza B viruses. Therefore, even if vaccine effectiveness is reduced against drifted circulating viruses, the vaccine will protect against non-drifted circulating vaccine viruses. Further, there is evidence to suggest that vaccination may make illness milder and prevent influenza-related complications. Such protection is possible because antibodies created through vaccination with one strain of influenza viruses will often “cross-protect” against different but related strains of influenza viruses;
(2) use of neuraminidase inhibitor medications when indicated for treatment or prevention. Antiviral treatment with oseltamivir or zanamivir is recommended as early as possible for any patient with confirmed or suspected influenza who: is hospitalized; has severe, complicated, or progressive illness; or is at higher risk for influenza complications. Antiviral chemoprophylaxis should be used for prevention of influenza when indicated for institutional influenza outbreaks, and may be considered for those who have contraindications to influenza vaccination. CDC recommends antiviral chemoprophylaxis for a minimum of two weeks, and continuing for at least seven days after the last known case was identified.
(3) use of other preventive health practices that may help decrease the spread of influenza, including respiratory hygiene, cough etiquette, social distancing (e.g., staying home from work and school when ill, staying away from people who are sick) and hand washing.
For More Information:
Influenza Vaccines Available in United States, 2014–15 Influenza Season
Information for healthcare professionals on the use of influenza antiviral medications:
Summary of Influenza Antiviral Treatment Recommendations for clinicians:
http://www.cdc.gov/flu/professionals/an ... tm#summary
Diagnostic Testing for Influenza:
http://www.cdc.gov/flu/professionals/an ... diagnostic
Interim Guidance for Influenza Outbreak Management in Long-Term Care Facilities:
http://www.cdc.gov/flu/professionals/in ... idance.htm
The Centers for Disease Control and Prevention (CDC) protects people's health and safety by preventing and controlling diseases and injuries; enhances health decisions by providing credible information on critical health issues; and promotes healthy living through strong partnerships with local, national and international organizations.
DEPARTMENT OF HEALTH AND HUMAN SERVICES
HAN Message Types
Health Alert: Conveys the highest level of importance; warrants immediate action or attention. Example: HAN00001
Health Advisory: Provides important information for a specific incident or situation; may not require immediate action. Example: HAN00346
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|Author:||niman [ Fri Dec 05, 2014 5:48 pm ]|
|Post subject:||Re: 76% of Newly Tested H3N2 in US Are Low Reactors|
A (H3N2) : Forty-eight (42%) of the 114 H3N2 viruses tested have been characterized as A/Texas/50/2012-like, the influenza A (H3N2) component of the 2014-2015 Northern Hemisphere influenza vaccine. Sixty-six (58%) of the 114 viruses tested showed either reduced titers with antiserum produced against A/Texas/50/2012 or belonged to a genetic group that typically shows reduced titers to A/Texas/50/2012. Among viruses that showed reduced titers with antiserum raised against A/Texas/50/2012, most were antigenically similar to A/Switzerland/9715293/2013, the H3N2 virus selected for the 2015 Southern Hemisphere influenza vaccine. A/Switzerland/9715293/2013 is related to, but antigenically and genetically distinguishable, from the A/Texas/50/2012 vaccine virus. A/Switzerland-like H3N2 viruses were first detected in the United States in small numbers in March of 2014 and began to increase through the spring and summer.
|Author:||niman [ Fri Dec 05, 2014 11:25 pm ]|
|Post subject:||Re: 76% of Newly Tested H3N2 in US Are Low Reactors|
CDC's flu warning raises questions about vaccine match
Filed Under: Influenza Vaccines; Influenza, General
Robert Roos | News Editor | CIDRAP News | Dec 05, 2014
The Centers for Disease Control and Prevention (CDC) warned yesterday that the profile of influenza viruses currently circulating, with A/H3N2 predominant, suggests a risk for a rough ride this winter, especially since about half of the H3N2 viruses don't match up with the corresponding strain in this year's vaccine.
CDC Director Tom Frieden, MD, MPH, observed that seasons dominated by H3N2 viruses are generally worse than other seasons, and warned that the mismatch between the vaccine and circulating strains may portend lower vaccine effectiveness (VE) than usual. Consequently, he emphasized that antiviral medications are an important second line of defense, especially for patients at risk for flu complications.
At a press conference, Frieden said the vaccine may still yield some protection against H3N2, despite the mismatch. At the same time, he cautioned that it's still early in the season and flu is highly unpredictable, so anything could happen.
In response to the CDC advisory, some flu experts raised questions about the wisdom of focusing public attention on findings of a vaccine mismatch with circulating flu strains. They say there seems to be little correlation between vaccine match and how well the vaccine works, and that even with an apparent mismatch, the vaccine should still provide some protection from infection. The critical point, they suggested, is that H3N2-dominated flu seasons tend to be more severe.
The CDC advice comes in the wake of a number of recent findings that have raised questions about the effectiveness of flu vaccines under various conditions. In November, for example, the CDC reported that the intranasal vaccine FluMist (live attenuated influenza vaccine, or LAIV) did not seem to be effective against H1N1 viruses in young children in the 2013-14 season. Other recent studies have suggested that getting a flu shot 2 years in a row may reduce the vaccine's effectiveness the second year.
On the other hand, some studies have indicated that the benefits of flu vaccination may last more than one season.
H3N2 viruses hold super-majority
At the press conference, Frieden said that about 90% of about 1,200 respiratory samples tested through the week before Thanksgiving week were type A viruses, and about 9% were type B.
Of the type A viruses, nearly all were H3N2, and about half of those were antigenically different from the H3N2 component of the vaccine, he explained. Today's FluView report from the CDC—which covers Thanksgiving week—placed the mismatch rate at 58%, up from 52% the week before (see related News Scan).
He said the "drifted" (slightly mutated) H3N2 viruses were first noticed in March, too late to include in this year's vaccine. "The H3 component of the vaccine was still by far the most common of the H3N2 viruses" at the time, he said, adding later that it wasn't until September that the new strain became common.
"Both strains are likely to continue to circulate in the US this season, and there's no way to predict what's likely to happen," Frieden said. "Only time will tell which of them, if any, will predominate for the following weeks and months of this season." He added that rates of hospitalization and death tend to be twice as high or more during H3N2-predominant seasons.
In a press release yesterday, the CDC said, "H3N2 viruses were predominant during the 2012-2013, 2007-2008, and 2003-2004 seasons, the three seasons with the highest mortality levels in the past decade. All were characterized as 'moderately severe.' "
Frieden said the circulating type B strains are well matched to the vaccine so far this season. "We continue to recommend flu vaccine as the best way to protect yourself against influenza," he added.
"The vaccine may have some effectiveness against the drifted [H3N2] strain," he said, adding later, "During some seasons when viruses are antigenically drifted, vaccine effectiveness can be lower, but not always."
In a Health Alert Network (HAN) notice this week, the CDC said that a poor vaccine match with circulating viruses has been associated with lower VE in past seasons, but it still provided some protection against drifted strains.
"Though reduced, this cross-protection might reduce the likelihood of severe outcomes such as hospitalization and death," the statement said. "In addition, vaccination will offer protection against circulating influenza strains that have not undergone significant antigenic drift from the vaccine viruses (such as influenza A (H1N1) and B viruses)."
Frieden noted that five children have died of flu-related causes this season. Joseph Bresee, MD, chief of the CDC's Influenza Epidemiology and Prevention Branch, said three of the children had H3N2 infections, but it is not known whether any of them involved the drifted strain.
The CDC officials also were asked about their report in November that LAIV did not seem to protect young children against H1N1 viruses in the 2013-14 season.
Frieden and Bresee said the CDC continues to recommend the use of FluMist in young children, or an injectable vaccine if it's not available. H1N1 viruses are uncommon so far this season, they added, and FluMist is likely to be effective against "matched strains." Also, they said they are continuing to investigate the earlier finding and what might explain it.
The potential for a tough flu season magnifies the importance of using the antiviral drugs oseltamivir (Tamiflu) and zanamivir (Relenza), particularly in patients who have chronic diseases that increase their risk for flu complications, Frieden said.
He said the drugs, when started early in the illness, can reduce the duration of symptoms and the risk of dying. "Antiviral drugs are very underprescribed," he added. "Probably fewer than one in six who are severely ill with flu get antiviral drugs. We need to get the message out that treating early with these drugs can make a difference between having a mild illness or a severe illness."
He said physicians should not wait for flu test results before prescribing an antiviral if otherwise indicated, and that patients who have flu symptoms and an underlying illness should seek treatment immediately.
Bresee said the CDC is not aware of any current antiviral shortages and expects the supply to meet the demand this season.
Similarly, Frieden said he's not aware of any flu vaccine shortages, other than a few spot shortages. He said 145 million doses of vaccine have been distributed, and that should be sufficient for the demand.
Questions on vaccine match and effectiveness
The CDC officials were asked about the correlation between vaccine match and VE and whether a better measure of VE is needed.
"It's clear that the laboratory tests we're using to understand how closely related this virus is to the vaccine virus are good, but they're imperfect markers of how well the vaccine will function in the field," Bresee replied, adding that the CDC conducts observational studies of VE each season.
"We'll have that data sometime in the middle of the season," he said. "You're right to the extent that these [tests of vaccine match] aren't perfect markers of what to expect in terms of how well the vaccine will work, but they are related to how well the vaccine works."
The relationship of vaccine match, as currently assessed, to VE has been questioned increasingly in recent years. The match is assessed using ferrets that have never been exposed to flu before. The animals are infected with one of the viruses targeted by the vaccine, and serum samples are subsequently collected. A hemagglutination inhibition (HI) test is then used to measure how well antibodies in the serum recognize and bind to other flu viruses, such as one isolated from a patient.
A drawback of this method, however, is that the ferrets are naive to flu, whereas humans other than young children have been exposed to many flu viruses and flu vaccines over the years. As a result, humans typically carry a whole library of flu antibodies, which makes their response to a virus much more complex than that of a ferret in a lab.
This fact was illustrated by a recent study described in Science, in which researchers conducted more than 10,000 HI tests to construct H3N2 "antibody landscapes" or profiles for 69 people over a wide range of ages. They found that titers were highest for antibodies that had circulated when individuals were about 6 years old and tended to be lower for newly circulating viruses than for earlier strains. Also, they found that infection with an H3N2 virus resulted in a "notably broad antibody response that was typically governed by the extent of the preexposure antibody landscape."
An outdated assessment?
Michael T. Osterholm, PhD, MPH, said he and his colleagues couldn't find a good correlation between vaccine match and VE when they conducted a rigorous meta-analysis of flu VE studies a few years ago. Osterholm is director of the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), publisher of CIDRAP News.
"It's become clear over the past several years that the current method for matching vaccine strains to circulating strains is almost an outdated assessment of the ability of a vaccine to protect against a strain of influenza," he said.
"The methods are such a crude indicator that they don't correlate highly with protection," he said. "For all we know, this [year's] vaccine could work as we'd expect to see it work in other years. Just because it's a bad match by this method doesn't mean it won't work. But if it's a good match, it doesn't necessarily mean it will be protective."
Osterholm also took issue with the CDC's suggestion that a mismatched flu vaccine, even if it doesn't prevent flu, may reduce the risk of severe outcomes like hospitalization. "There is no convincing evidence that, if you get vaccinated with a vaccine that is not well matched to the circulating strain using our current test methods, there is any reduction in disease severity or mortality," he said, adding that the same caveat applies even if the vaccine seems well-matched to circulating viruses.
"That's an unfortunate statement that is part of what has historically been an overstatement of the public health impact of flu vaccine."
However, he added that he still recommends vaccination as the best available tool for preventing flu. He also agreed about the importance of the message that H3N2-dominated flu seasons are generally worse than those dominated by other flu varieties.
H3N2 dominance seen as main concern
Edward Belongia, MD, director of the Epidemiology Research Center at the Marshfield Clinic Research Foundation in Wisconsin, agreed that the association between vaccine match and effectiveness is fuzzy and said that the primary concern now is the likelihood of an H3N2-dominated flu season. Belongia participates in the CDC's US Flu Vaccine Effectiveness Network.
"The relationship between vaccine match as currently defined and actual clinical vaccine effectiveness is not very clear," he said. "One of the unfortunate aspects of the interpretation of this CDC advisory is that some media are interpreting it as saying the vaccine won't work this year.
"The CDC advisory sort of raises a lot of questions and doesn't provide a lot of clarity. The most important thing to keep in mind, really more important than the antigen match question, is that this is going to be an H3N2 season. We know we have more hospitalizations and more deaths in an H3N2 season. The other thing is that in general the vaccine effectiveness is not as high in an H3N2 season as in other seasons."
Belongia said the vaccine should provide some protection against H3N2 viruses even if there's a mismatch. Speaking of flu vaccines in general, he said, "We tend to see protection in the 40% to 60% range, regardless of match or mismatch. Sometimes it's a little less than that for H3N2."
He added, "The relationship between the antigenic match or mismatch and actual protection is not straightforward, and it's not correct . . . to conclude that the vaccine is not effective or less effective."
When there's a "huge" mismatch between the vaccine and a circulating strain, such as when the 2009 pandemic H1N1 virus emerged, "there's no question that you're not going to be protected," Belongia said. "But when you have this mild antigenic drift, what that means for vaccine effectiveness is not clear and may not be the same for different age-groups."
He agreed with Osterholm on the question of whether a vaccine can limit the severity of illness even if it fails to prevent flu in the first place: "I don’t think there's any convincing evidence that the vaccine, if not preventing flu, is still giving you a milder illness."
He and his colleagues did a multi-season study of whether outpatients who got sick with flu were less likely to be hospitalized if they had been vaccinated. "The answer was no. Once you got flu, whether you were vaccinated or not, it had no effect on the likelihood of being hospitalized."
He added that some studies have hinted that vaccination may be linked to a reduction in severity of illness, but the findings were not conclusive.
Belongia also commented that he agreed with the CDC's advice about the importance of antiviral treatment for high-risk patients. "That advice applies in any season, and especially in an H3N2 season. I don't think whether some of the viruses are drifted is really the main message here."
Dec 4 CDC press release
Dec 3 CDC HAN notice
Transcript of Dec 4 CDC press briefing
Nov 7 CIDRAP News story about LAIV effectiveness against H1N1 in kids
Nov 26 CIDRAP News story on effects of consecutive-year flu shots
CDC information on how antigenic match is assessed
Nov 21 Science abstract on human flu antibody landscapes
http://www.cidrap.umn.edu/news-perspect ... cine-match
|Author:||niman [ Fri Dec 12, 2014 12:32 pm ]|
|Post subject:||Re: 76% of Newly Tested H3N2 in US Are Low Reactors|
week 49 data
|Author:||niman [ Fri Dec 19, 2014 12:18 pm ]|
|Post subject:||Re: 76% of Newly Tested H3N2 in US Are Low Reactors|
Preparing for Influenza: An H3N2 Season with a Vaccine Mismatch
Amesh A. Adalja, MD, FACP, FACEP, December 19, 2014
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As this year's flu season begins to pick up speed, early indicators point to a particularly severe season. Thus far, flu activity has not been widespread across most of the nation, but several southern states have been reporting high rates of influenza, and as we approach the traditional peak of flu activity (February), the nation will follow suit. Thus far, 7 pediatric deaths have been reported.1
Flu Vaccine Mismatch
One factor that will likely play a major role in the severity of the season is the mismatch of the H3N2 component of the now quadrivalent vaccine. This season the dominant H3N2 virus is a "drift" variant from the vaccine strain--a phenomenon that happens from time to time. This is ominous because H3N2 is the dominant strain so far this year.
In the week ending December 6, 2014, the CDC reported that, of subtype flu A viruses, all but 7 A isolates were H3N2 and virtually all of these were the drift variant. There has been almost no H1N1 this year, and influenza B has been responsible for only 4.8% of flu cases this season.1
H3N2-dominant seasons tend to be more severe than seasons dominated by other strains and are characterized by a particular predilection to attack the very young and the very old, the populations at highest risk for severe influenza.2 Because of the mismatch of the vaccine this season, the chief means to prevent complications from influenza will be the use of neuraminidase inhibitors. Adamantane drugs (such as rimantadine) should be avoided because of high rates of resistance to them among circulating flu viruses of all types. Clinicians must promptly prescribe either oseltamivir or zanamivir to those suspected of having influenza. However, in those with delayed presentations or diagnosis, antiviral therapy will likely still have benefit (as shown in retrospective analyses).3
Although the vaccine being employed for the upcoming season in the southern hemisphere will include the new H3N2 variant, the fact that another mismatched season has occurred, despite the development of a quadrivalent vaccine, underscores the need for a game-changing vaccine. Such a vaccine would be directed against a universal antigen of the virus, leaving no room for drift variants to derail it.
Weekly U.S. influenza surveillance report. Centers for Disease Control and Prevention website. Updated December 12, 2014. http://www.cdc.gov/flu/weekly/. Accessed December 16, 2014.
Adalja AA. Comparing severity and outcomes for seasonal and 2009 H1N1 infections. JAMA 2011;305:39-40.
Viasus D, Pano-Pardo JR, Pachon J, et al. Timing of oseltamivir administration and outcomes in hospitalized adults with pandemic 2009 influenza A(H1N1) virus infection. Chest 2011;140:1025-1032.
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