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WHO Insists Tamiflu-Resistant Swine Flu Is Isolated Case

Posted on: Wednesday, 1 July 2009, 08:35 CDT

After the first reported case of an H1N1 patient not responding to the antiviral drug Tamiflu, the World Health Organization (WHO) assured the public that it was an isolated case.

The swine flu has been declared as a global pandemic by the United Nations agency, and up to this point it has proven to be treatable with the drug Tamiflu made by Roche.

WHO spokesman Dick Thompson says that the case of the man in Denmark whose infection was not responding to the drug, which Danish officials and the Swiss company reported on Monday, does not mean the virus has increased in its severity.

"This is an isolated case. At this time, there is no public health implication. But we must remain alert as the virus can change at any time and we must not be complacent," he told Reuters.

The patient is reportedly doing well with no detectable contagion with the drug-resistant virus.

Thompson also pointed out that instances of resistance to Tamiflu were previously documented for avian flu, but this is the first case of swine flu not responding to the treatment.

"We need to monitor the virus (H1N1) continuously," he said, adding that the WHO's global influenza surveillance network connecting laboratories in 97 countries would continue monitoring it.

"WHO is not changing its recommendations for the use of antivirals," Thompson added, referring to the global body's advice to its 193 member states.

The WHO previously listed a class of antiviral drugs that the H1N1 virus is sensitive to, which includes Tamiflu, known generically as oseltamivir, and Relenza by GlaxoSmithKline, known generically as zanamivir.

Denmark's State Serum Institute said in their announcement on Monday that they expected the strain to mutate to become resistant to Tamiflu eventually.

It said that though the particular strain of the virus infecting the patient had mutated to a form resistant to Tamiflu, Relenza still remained a viable treatment.

On June 11, the WHO raised its pandemic flu alert to its highest level of 6, giving indication that the first influenza pandemic since 1968 had arrived.

Flu viruses are constantly and rapidly mutating and can become resistant to drugs at any point.

Some health experts are expressing concern that even though Tamiflu is currently effective against the strains of the new flu, it might become less effective than Relenza, since its distant relative, the seasonal flu, has been widely reported as being resistant to Tamiflu.

David Daigle, a spokesman for the U.S. Centers for Disease Control and Prevention, said that the isolated case in Denmark would not justify changing the recommended uses of Tamiflu.

"The resistance has not changed the capability of the virus to transmit or cause disease, and the assessment is still that this is a relatively mild influenza," he said on Monday.

At least 20 companies make flu vaccines, including Novartis, Sanofi-Aventis, GlaxoSmithKline, Baxter International, Solvay, Australia's CSL and nasal spray maker MedImmune, now part of AstraZeneca.

The French drug maker Sanofi-Aventis that makes an estimated 40% of the world's supply of flu vaccine said that it had started a large-scale production of a H1N1 vaccine through its Sanofi-Pasteur unit this month.

Novartis said its vaccine is expected to be available by autumn and Baxter International has said it is in full-fledge production of a vaccine that could be available for commercial use as early as July.

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On the Net:

• WHO
• CDC

Source: redOrbit Staff & Wire Reports

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