U.S. flu shows resistance to flu drug, CDC says

[Shiloh]

Source: http://www.reuters.com/article/healt...4BI4HY20081219

U.S. flu shows resistance to flu drug, CDC says
Fri Dec 19, 2008 12:48pm EST

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - A common strain of influenza circulating in the United States this winter is resistant to Tamiflu, the most popular drug used to treat it, federal health officials said on Friday.

The situation poses little danger, according to the U.S. Centers for Disease Control and Prevention, because Tamiflu is only used in a minority of cases. It advised doctors to use rival drug Relenza or rimantadine, an older drug.

Forty nine out of 50 samples tested resist the drug, although they can still be treated with other flu medications, the CDC said in a special advisory to doctors.

"It is still very early in the season. There is very little influenza out there," CDC Director Dr. Julie Gerberding told reporters in a telephone briefing.

"This is probably actually not going to affect very many people because we don't use a lot of antiviral drugs in our country," Gerberding said. "Most people with influenza don't get any treatment."

In a normal flu season, three strains of flu circulate called H1N1, H3N2 and influenza B. Flu kills about 36,000 Americans in an average year.

It is the H1N1 strain that is turning up resistant samples, Gerberding said, and comes mostly from Hawaii, Massachusetts and Texas, the states with the most cases of influenza.

Last year, just under 11 percent of the H1N1 samples tested were resistant to Tamiflu. Gerberding said she did not think the virus had evolved, but that the strain that happened to pop up was also resistant to the drug.

"We can't predict whether or not these strains will end up being the most important strains in this year's flu season. This particular H1N1 could fizzle out," Gerberding said.

Tamiflu, known generically as oseltamivir and made by Roche AG and Gilead Sciences Inc., can both prevent and treat flu if taken quickly enough.

A similar drug is Relenza, or zanamivir, made by GlaxoSmithKline under license from Australia's Biota Inc..

The U.S. national stockpile of antivirals is about 80 percent Tamiflu and 20 percent zanamivir, according to the Health and Human Services Department. The CDC's Dr. Tim Uyeki said this season's development illustrated the need to keep a diversified array of drugs on hand.

"But zanamivir ... is not approved for those less than 7 years old," Uyeki said. People with asthma are also advised not to use the drug, which is inhaled.

Gerberding noted that this year's flu vaccine matched the three strains circulating so far very well. The CDC says there is still time for Americans to get a flu shot, as the season usually peaks in February.

The CDC and the U.N. World Health Organization are concerned about the threat of a new and deadly strain of flu developing that would sweep the world. That is one reason to keep a stockpile of antivirals handy, CDC says, although this year's flu season appears to be mild.

(Editing by Alan Elsner and Will Dunham)

[HenryN]

Re: U.S. flu shows resistance to flu drug, CDC says

Better late than never.

[HenryN]

Re: U.S. flu shows resistance to flu drug, CDC says

Sick with the flu? CDC says Tamiflu doesn't seem to work against most common flu bug right now

By MIKE STOBBE
AP Medical Writer
1:59 PM CST, December 19, 2008
ATLANTA (AP) — The medical arsenal against the flu just got weaker.

Government health officials said Friday that a leading flu medicine, Tamiflu, might not work against all cases of the flu this year. The most common flu bug right now is overwhelmingly resistant to Tamiflu, they said.

The alert is "an early heads-up" for doctors. If current trends continue, they may need to change how they treat patients this flu season, said Dr. Julie Gerberding, director of the U.S. Centers for Disease Control and Prevention.

Health officials say they aren't too worried, for several reasons. First, it's early in the flu season, and it's not clear this strain will dominate through the next several months. Second, not many people take antiviral medications for the flu.

Third, the flu vaccine — the primary weapon against flu — seems well matched against the circulating bugs.

But doctors need to take it seriously, said William Schaffner, a Vanderbilt University infectious diseases expert.

"Each influenza seasons provides a bit of a surprise and we got our (surprise) a little early this year," he added.

The flu causes 200,000 hospitalizations and 36,000 deaths annually, according to official estimates. The elderly, young children and people with chronic illnesses are considered at greatest risk.

For the public, the best course of action is vaccination, health officials said. Only about 30 percent of U.S. adults had gotten a flu vaccination this flu season, according to an online survey conducted by the RAND Corporation in November. A flu shot is recommended for those 50 and older, children from 6 months to 18 years, pregnant women, nursing home patients and those with certain medical conditions or who care for people with those conditions.

For people who get the flu, the two most commonly used antivirals are Tamiflu, a pill also known as oseltamivir, and Relenza, an inhaled drug also called zanamivir. The drugs are most effective if taken within two days of getting sick but most people don't see a doctor that quickly.

Early tests indicate that 49 of 50 samples of the main flu virus circulating this year — H1N1 — were resistant to Tamiflu. The samples came mainly from Hawaii, Texas and ten other states. Widespread flu has not yet been reported in most of the country.

"It could fizzle out," or H1N1 could become the dominant strain, Gerberding said.

A spokesman for Tamiflu's manufacturer — Roche, a Swiss company — said it's too early to draw strong conclusions about the drug's usefulness this flu season. The basis of the CDC's alert "is a small sample in a limited number of states, and Tamiflu is showing good activity against other circulating viruses," said spokesman Terry Hurley.

For those sick with the flu, doctors cannot simply choose Relenza instead of Tamiflu. That treatment is not approved for children younger than 7 or people who have asthma or certain other breathing problems. GlaxoSmithKline PLC, which makes Relenza, said Friday it has enough to meet the demands of the current flu season.

An option for some patients, Gerberding said, may be a combination of Tamiflu and rimantadine, another antiviral medication that works against H1N1 but lost effectiveness against another kind of flu virus.

However, it's not clear how well that combination will work, Schaffner said.

"This is a 'best advice with our back against the wall' kind of thing," he said.

___

On the Net:

The CDC flu report: http://www.cdc.gov/flu/weekly/

http://www.chicagotribune.com/features/lifestyle/health/sns-ap-med-flu-drug-resistance,0,6794348,print.story

[Giuseppe]

Re: U.S. flu shows resistance to flu drug, CDC says

Uncomplicated seasonal influenza infections in otherwise healthy population may be ''cured'' without antivirals since the danger of resistant variants circulation.

People should aware of simple tips to monitoring their health condition during an influenza attack, and if uncommon features should emerge - fever ''resistant'' to common remedies, cough, shortness of breath, and after seek medical advice - to visit local outpatient clinics for further health checks.

In this perspective a correct and timely media coverage of influenza season and clinical presentation is warranted, even for avoid use of antibiotics or other drugs with potential adverse effects in adults and children.

However, when media coverage tends to exaggerate or misinform, the result may be the overflow of medical facility, overwhelmed personnel and overuse of drugs.

[HenryN]

Re: U.S. flu shows resistance to flu drug, CDC says

Commentary

http://www.recombinomics.com/News/12190803/H274Y_CDC.html

[Giuseppe]

Re: U.S. flu shows resistance to flu drug, CDC says

CDC - Influenza (Flu) | Interim Recommendations for the Use of Influenza Antiviral Medications in the Setting of Oseltamivir Resistance, 2008-09

Interim Recommendations for the Use of Influenza Antiviral Medications in the Setting of Oseltamivir Resistance among Circulating Influenza A (H1N1) Viruses, 2008-09 Influenza Season

Persons providing medical care for patients with suspected influenza or persons who are candidates for chemoprophylaxis against influenza should consider the following guidance for assessing and treating patients during the 2008-09 influenza season (see attached Antiviral Guidance Table):

1. Review local or state influenza virus surveillance data weekly during influenza season, to determine which types (A or B) and subtypes of influenza A virus (H3N2 or H1N1) are currently circulating in the area. For some communities, surveillance data might not be available or timely enough to provide information useful to clinicians.

2. Consider use of influenza tests that can distinguish influenza A from influenza B.
-- 1. Patients testing positive for influenza B may be given either oseltamivir or zanamivir (no preference) if treatment is indicated.
-- 2. At this time, if a patient tests positive for influenza A, use of zanamivir should be considered if treatment is indicated. Oseltamivir should be used alone only if recent local surveillance data indicate that circulating viruses are likely to be influenza A (H3N2) or influenza B viruses. Combination treatment with oseltamivir and rimantadine is an acceptable alternative, and might be necessary for patients that cannot receive zanamivir, (e.g., patient is <7 years old, has chronic underlying airways disease, or cannot use the zanamivir inhalation device), or zanamivir is unavailable. Amantadine can be substituted for rimantadine if rimantadine is unavailable.
-- 3. If a patient tests negative for influenza, consider treatment options based on local influenza activity and clinical impression of the likelihood of influenza. Because rapid antigen tests may have low sensitivity, treatment should still be considered during periods of high influenza activity for persons with respiratory symptoms consistent with influenza who test negative and have no alternative diagnosis. Use of zanamivir should be considered if treatment is indicated. Combination treatment with oseltamivir and rimantadine (substitute amantadine if rimantadine unavailable) is an acceptable alternative. Oseltamivir should be used alone only if recent local surveillance data indicates that circulating viruses are likely to be influenza A (H3N2) or influenza B viruses.
-- 4. If available, confirmatory testing with a diagnostic test capable of distinguishing influenza caused by influenza A (H1N1) virus from influenza caused by influenza A (H3N2) or influenza B virus can also be used to guide treatment. When treatment is indicated, influenza A (H3N2) and influenza B virus infections should be treated with oseltamivir or zanamivir (no preference). Influenza A (H1N1) virus infections should be treated with zanamivir or combination treatment with oseltamivir and rimantadine is an acceptable alternative.

3. Persons who are candidates for chemoprophylaxis (e.g., residents in an assisted living facility during an influenza outbreak, or persons who are at higher risk for influenza-related complications and have had recent household or other close contact with a person with laboratory confirmed influenza) should be provided with medications most likely to be effective against the influenza virus that is the cause of the outbreak, if known. Respiratory specimens from ill persons during institutional outbreaks should be obtained and sent for testing to determine the type and subtype of influenza A viruses associated with the outbreak and to guide antiviral therapy decisions. Persons whose need for chemoprophylaxis is due to potential exposure to a person with laboratory-confirmed influenza A (H3N2) or influenza B should receive oseltamivir or zanamivir (no preference). Zanamivir should be used when persons require chemoprophylaxis due to exposure to influenza A (H1N1) virus. Rimantadine can be used if zanamivir use is contraindicated.

Enhanced surveillance for influenza antiviral resistance is ongoing at CDC in collaboration with local and state health departments. Clinicians should remain alert for additional changes in recommendations that might occur as the 2008-09 influenza season progresses. Oseltamivir resistant influenza A (H1N1) viruses are antigenically similar to the influenza A(H1N1) viruses represented in the vaccine, and vaccination should continue to be considered the primary prevention strategy regardless of oseltamivir sensitivity. Information on antiviral resistance will be updated in weekly surveillance reports (available at http://www.cdc.gov/flu/weekly/fluactivity.htm)

For more information on antiviral medications and additional considerations related to antiviral use during the 2008-09 influenza season, visit http://www.cdc.gov/flu/professionals...rals/index.htm.

Note: This information is the summary portion of a Health Alert Advisory issued on December 19, 2008 entitled Interim Recommendations for the Use of Influenza Antiviral Medications in the Setting of Oseltamivir Resistance among Circulating Influenza A (H1N1) Viruses, 2008-09 Influenza Season." Visit http://www.cdc.gov/flu/professionals...rals/index.htm for the full content of the interim recommendations.

<cite cite="http://www.cdc.gov/flu/professionals/antivirals/recommendations.htm">CDC - Influenza (Flu) | Interim Recommendations for the Use of Influenza Antiviral Medications in the Setting of Oseltamivir Resistance, 2008-09</cite>

[Sally Furniss]

Re: U.S. flu shows resistance to flu drug, CDC says

Flu Strain Has Resistance to Roche’s Tamiflu in U.S. (Update3)
By Tom Randall
<!-- WARNING: #foreach: $wnstory.ATTS: null at /bb/data/web/templates/webmacro_en/washingtonstory.wm:266.2 --> <!-- WARNING: #foreach: $wnstory.ATTS: null at /bb/data/web/templates/webmacro_en/washingtonstory.wm:280.19 --> Dec. 19 (Bloomberg) -- A strain of influenza virus in the U.S. was found to be resistant to Roche Holding AG’s Tamiflu, prompting U.S. health officials to recommend rival treatments.

Doctors prescribing antiviral treatments should give their patients GlaxoSmithKline Plc’s Relenza or a combination of Tamiflu and an older drug called rimantadine, the Centers for Disease Control and Prevention said in an e-mailed statement. Roche had worldwide Tamiflu sales of $2.09 billion last year.

The flu season is just beginning, with few or no cases reported in most U.S. states, the Atlanta-based CDC said. This year’s vaccine, redesigned annually to protect against three types of flu, appears to be a good match with the strains that are circulating, the CDC said. The agency encouraged people to get the shots before cases increase in coming months.

“Over the course of the season, things change,” said Tony Fiore, an infectious disease doctor at the CDC and an author of the report. “Whether the resistance is going to be a significant problem this year isn’t evident yet.”

Several types of flu are currently circulating in the U.S. Only one, H1N1, shows resistance to Tamiflu. Last year, H1N1 was the least resistant strain of flu, and 11 percent of H1N1 cases were resistant, Fiore said. In contrast, this year the strain is the most prevalent, and 95 percent of H1N1 cases resist Tamiflu, he said.

Fruity Flavor

Relenza, which is taken through an inhaler and only approved for children older than age 6, hasn’t shown resistance to any of the strains. More people take Tamiflu, available as a pill or fruit-flavored liquid, because it’s easier to administer and approved for use in young children, Fiore said.

“It’s early in the season, and the flu is unpredictable,” said Terence Hurley, a spokesman for Roche. “This is a small sample in a limited number of states, and Tamiflu has shown good activity against the other strains.”

Flu season in the U.S. typically lasts from November through March, according to the CDC. The virus strikes 5 percent to 15 percent of the population and kills 250,000 to 500,000 people a year worldwide, according to the World Health Organization.

American depositary receipts for Roche, based in Basel, Switzerland, declined 99 cents, or 1.4 percent, to $71.65 at 3:59 p.m. New York time in over-the-counter trading. Each receipt equals one-half a regular company share.

To contact the reporter on this story: Tom Randall in New York at trandall6@bloomberg.net .
Last Updated: December 19, 2008 16:36 EST

http://www.bloomberg.com/apps/news?pid=washingtonstory&sid=aZ7t1xCzLU6k

[AlaskaDenise]

Re: U.S. flu shows resistance to flu drug, CDC says

Commentary

http://www.recombinomics.com/News/12...H274Y_CDC.html

Commentary


CDC Advises Against Tamiflu Treatment of Seasonal Flu
Recombinomics Commentary 20:33
December 19, 2008


It advised doctors to use rival drug Relenza or rimantadine, an older drug.

Forty nine out of 50 samples tested resist the drug, although they can still be treated with other flu medications, the CDC said in a special advisory to doctors.

The above comments acknowledge the current level of Tamiflu resistance in the United States and notes the special advisory issued by the CDC which eliminates the recommendation mismatch that existed prior to the advisory.

The new data indicates that the only oseltamivir sensitive isolate reported by the CDC is the clade IIC isolate from California. Thus, all clade IIB (Brisbane) is oseltamivir resistant.

The week 50 update for Europe had the same result. There was only one oseltamivir sensitive H1N1 isolate reported and that isolate was also almost certainly clade IIC because there was one isolate that was adamantadine resistant, which is found in clade IIC isolates. Thus, 100% of reported clade IIB in North America and Europe has H274Y.

Moreover, in the United States, the vast majority of influenza A is H1N1, which created the recommendation mismatch. In Europe, most influenza A reported to date is H3N2, which is 100% oseltamivir sensitive, so the prior recommendations for Europe are appropriate.

However, clade IIB is dominating H1N1 in circulation, which has serious implications for pandemic concerns because H274Y can be acquired via recombination, and H5N1 with H274Y is fit.

.

[Shiloh]

Re: U.S. flu shows resistance to flu drug, CDC says

Source: http://www.torontosun.com/news/world...12346-sun.html


Saturday, December 20, 2008
News World
Flu bugs give docs headache

By HELEN BRANSWELL, THE CANADIAN PRESS
Last Updated: 20th December 2008, 3:50am

Early signs from this flu season suggest doctors face a vexing dilemma. Testing to date shows the viruses are resistant to some of the drugs commonly used to treat them.

Nearly all H1N1 viruses are resistant to oseltamivir (sold as Tamiflu) and responsive to adamantane, amantadine and rimantadine. The opposite is true for H3N2 viruses.

Given that little testing is done to determine whether a patient actually has influenza, let alone which variety of the bug, the resistance situation could mean doctors will make treatment choices that fail.

"This is a very challenging situation," Dr. Tim Uyeki, deputy chief of influenza surveillance for the U.S. Centers for Disease Control admitted.

"It definitely adds to the complexity of trying to manage influenza," Dr. Maria Zambon, head of the respiratory viruses unit of Britain's Health Protection Agency, agreed.

In the face of these early results, the CDC issued a health alert yesterday to recommend changes in the usage of flu drugs for the time being.

The upshot? When in doubt -- and when the patient's age and health permits -- use the only other option, the drug zanamivir, which is sold under the brand name Relenza. So far, all influenza A viruses (H1N1 and H3N2 are subtypes of influenza A) as well as influenza B viruses seem to respond to zanamivir.

[HenryN]

Re: U.S. flu shows resistance to flu drug, CDC says

INFLUENZA A (H1N1) VIRUS, OSELTAMIVIR RESISTANCE (09): UNITED STATES OF AMERICA
************************************************** *****************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: Sat 20 Dec 2008
Source: Topnews oline [edited]
<http://topnews.us/content/21026-cdc-warns-tamiflu-resistant-flu-bug>


CDC Warns of Tamiflu Resistant Flu Bug
--------------------------------------
The U.S. Centers for Disease Control and
Prevention (CDC) warned in an official health
advisory to doctors that the most common flu bug
that is spreading in the U.S. is resistant to the
flu drug Tamiflu [oseltamiver]. The
Tamiflu-resistant virus is the flu bug most
commonly seen so far this year [2008] and has
been detected in 12 states so far, mostly in
Hawaii and Texas. The strain is not more or less
dangerous than other flu strains. Medical experts
say Tamiflu resistance was not unexpected though
the speed of Tamiflu resistance was surprising.
Last year 11 percent of type A H1N1 flu bugs were
resistant while this year, 49 out of 50 H1N1 viruses have been resistant.

CDC Director Julie Gerberding, MD, said, "There
is no crystal ball here. We can't predict if this
strain will end up being the most important one
this year. It could fizzle out. ... We're giving
a 'heads-up' to the clinicians, but we are not
making drastic changes in our treatment and prevention recommendations."

There are no ways of knowing this early in the
flu season if Tamiflu resistant flu bug will be
this year's predominant cause of the flu. In
humans 3 different flu bugs are in circulation,
with type A H3N2 strain, one type B strain and
the resistant bug is the type A H1N1 strain.
Gerberding said the current flu vaccine protects
against all 3 of the viruses and is an excellent
match for the drug resistant bug.

Tamiflu which can run USD 100 a box, has been the
most attractive treatment because it is taken in
pill form and can be given to children as young
as one year old. There are alternatives for the
flu such as Relenza, which the Tamiflu-resistant
flu bug is still sensitive to as well as older
drugs such as [the adamantanes] Flumadine and
Symmetrel, although resistance to these drugs has
been steadily increasing among type A flu bugs.

Relenza which comes in an inhaler cannot be used
for children younger than 7 for treatment, and
those younger than 5 can't use it for prevention.
Moreover, Relenza sometimes causes lung spasms,
so it can't be used by people with lung problems.

Joseph S. Bresee, MD, chief of the epidemiology
and prevention branch of the CDC's flu division
said, "Even among hospital patients with the flu,
more than half do not receive antiviral therapy.
Tamiflu and Relenza are relatively underused at
this point. He said that the current warning may
actually see an increase in the use of flu drugs
by increasing awareness in doctors on how to use them.

[Byline: Jason Ramsey]

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[A more precise statement of the situation at the
the middle of December 2008 is the following.

Europe - (from the Cumulative virological
situation � 2008-2009 season (weeks 40-50/2008).
See the EISS Weekly Electronic bulletin:
<http://www.eiss.org/cgi-files/bulletin_v2.cgi>:

"No antiviral resistance against neuraminidase
inhibitors was detected in the 27 A (H3N2) virus
isolates tested so far this season. Of the 26
A(H3N2) isolates that were also tested for
adamantanes susceptibility, all were resistant.
In addition, out of the 20 A (H1N1) virus
isolates tested for resistance against
neuraminidase inhibitors, 19 were
oseltamivir-resistant, but all were sensitive to
zanamivir and only 1 of 11 tested was resistant
to adamantanes. The one type B isolate tested was
sensitive to both oseltamivir and zanamivir."

United States - (from Update: Influenza Activity
--- United States, Sep 28--Nov 29, 2008). See: MMWR Weekly 12 Dec 2008
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5749a3.htm>.

"With limited influenza activity in the United
States, few viruses have been available for
antiviral resistance testing. Since 28 Sep 2008,
39 influenza viruses from 11 states have been
tested for antiviral resistance; of the viruses
tested, 28 (71.8 percent) were collected from
only 2 states. Preliminary data show that 24 of
the 25 influenza A (H1N1) isolates tested were
resistant to oseltamivir; all H1N1 isolates were
sensitive to zanamivir. All 5 influenza A (H3N2)
and the 9 influenza B isolates tested were
sensitive to oseltamivir and zanamivir. 25
influenza A (H1N1) isolates and 5 influenza A
(H3N2) isolates were tested for adamantane
resistance. All influenza A (H1N1) isolates were
sensitive to adamantanes, and all influenza A
(H3N2) isolates tested were resistant to
adamantanes. The adamantanes are not effective against influenza B viruses."

Ths the prevalence of oseltamivir-resistant
influenza A virus is not dissimilar throughout
the northern hemisphere at least. - Mod.CP]

[see also:
Influenza A (H1N1) virus, oseltamivir resistance (08): Europe 20081025.3375
Influenza A (H1N1) virus, oseltamivir resistance (07): Europe 20080906.2783
Influenza A (H1N1) virus, oseltamivir resistance
(06): S. Hemisphere 20080825.2648
Influenza virus, oseltamivir resistance (06): Japan 20080228.0812
Influenza A (H1N1) virus, oseltamivir resistance
(05): China (HK) 20080203.0438
Influenza A (H1N1) virus, oseltamivir resistance (03): corr. 20080203.0430
Influenza A (H1N1) virus, oseltamivir resistance (04): CA, USA 20080202.0428
Influenza A (H1N1) virus, oseltamivir resistance (03): Europe 20080201.0399
Influenza A (H1N1) virus, oseltamivir resistance (02): Europe 20080129.0371
Influenza A (H1N1) virus, oseltamivir resistance - Norway 20080128.0361
2006
----
Avian influenza, human (162): oseltamivir resistance 20061010.2907]
.........................cp/ejp/dk