May 20, 2009

Officials Fear New H1N1 Could Mix With Drug-Resistant Strains

Officials with the U.S. Centers of Disease Control and Prevention (CDC) said Tuesday that they fear the widespread H1N1 influenza virus could mix with drug-resistant versions of seasonal flu.

To date, there are more than 100,000 H1N1 infections in the United States, which have resulted in a range of illnesses and seven deaths, the CDC said.  For now, the disease responds well to treatment with antiviral drugs.

However, this year the virus' cousin, a seasonal H1N1 strain, became resistant to the most common antiviral treatment, Tamiflu.  The inhaled drug Relenza, made by GlaxoSmithKline, still works.

According to the CDC, for reasons not yet known, more seasonal flu viruses were making people sick than would typically be expected for May.

"We think that it may be as much as half, or even more, of the viruses that we are testing now ... are the new H1N1 or cannot be subtyped," said the CDC's Dr. Anne Schuchat during a telephone briefing with Reuters.

"The particular risk here ... is that co-circulation of this new virus together with the seasonal strains might put us at risk for there to be a reassortment event," she said.

Reassortment is when two viruses meet and can exchange entire sequences of their genetic material.  Flu viruses are particularly prone to this, and some pandemics have emerged because of this reassortment.  Flu viruses can also mutate by making mistakes when they replicate.

The seasonal H1N1 that circulated this year was so resistant to Tamiflu that the CDC recommended not even treating flu patients with the drug this year.

"We would hate to see this novel strain essentially become resist through that mechanism," said Schuchat.

According to CDC data, there have are now 5,469 confirmed cases of the new flu throughout most of the United States.  However, Schuchat has said this is only the tip of the iceberg.  

Last week CDC acting director Dr. Richard Besser estimated there were some 100,000 cases.

The seventh U.S. death was reported on Tuesday by officials in St. Louis County, Missouri, where a 44-year-old man with no known underlying medical problems was believed to have died from an H1N1 infection. 

In California, state health officials released details of 30 of the state's early serious cases of H1N1.  The data included details of a prematurely born baby who had been infected in the hospital, and several people with serious medical conditions.

"About two-thirds of the patients ... had at least one underlying condition that put them at risk," said Schuchat.

Five of the victims were pregnant women, something the CDC also warned about last week.  Pregnancy can make a woman more vulnerable to complications from any kind of flu.  Schuchat said that some are still in the hospital with very severe illness.

While seasonal flu co-infections with bacteria can often result in more serious disease, that was not the case in any of the new H1N1 cases investigated, Schuchat added.

"We were surprised by the frequency of obesity among the severe cases that we are tracking," Schuchat said, adding that it is unclear whether being obese makes a patient more vulnerable or if the numbers simply reflect how common obesity is within the general population.

Separately, a spokesman for GlaxoSmithKline said the company has offered to donate 50 million doses of a pandemic vaccine to the World Health Organization (WHO) in the event of a global outbreak.
The offer was made during a meeting with U.N. officials, vaccine manufacturers and health experts to discuss how to provide vaccines to poor countries in the event of a global pandemic. 

However, the offer has not been finalized by GlaxosmithKline or WHO. Several vaccine makers in developing nations have also offered to share their vaccines, but their production capacity is limited.

WHO chief Margaret Chan and U.N. Secretary General Ban Ki-moon called on drugmakers to save some of their pandemic vaccines for poor nations. Glaxo spokesman Stephen Rea said the company would reduce its pandemic vaccine prices for poor and developing nations.

Although no pandemic vaccine currently exists, pharmaceutical firms say they can start production immediately once they obtain the vaccine's key ingredient, a so-called "seed stock" based on the virus. The WHO said the CDC is currently developing a seed stock, which should be available by mid-July.  A vaccine is expected to be available several months later.

Glaxo has also signed deals with various nations to provide pandemic vaccines as soon as they are available.   It has pledged to provide 60 million doses to Britain, 12.6 million doses for Belgium and 5.3 million doses for Finland.   It is also working on finalizing an agreement with France that would provide the nation with 50 million vaccines.

To date, the other leading vaccine makers have not followed Glaxo's lead in offering to donate vaccines. Swiss pharmaceutical firm Novartis AG said it had not changed its position on vaccine access for poor countries since the issue initially came to the fore in connection with the H5N1 bird flu.

"It's pretty much the status of discussions two years ago," Novartis spokesman Eric Althoff told the Associated Press.

"I don't think that all of the answers are there yet."


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