Washington Editor

WASHINGTON - While the Centers for Disease Control and Prevention (CDC) has isolated a seed strain and researchers are busy growing it for potential manufacturing of a vaccine against the 2009 H1N1 influenza A virus, nothing yet has been distributed to manufacturers for production, the acting head of the agency told reporters Thursday.

The current working plan, said Richard Besser, is to have manufacturers complete their production of seasonal influenza vaccines and then switch over to producing a vaccine against the new H1N1 strain, with a product available possibly by the fall.

However, he said, the government's current focus is ensuring a seasonal flu vaccine is available in adequate supplies for the 2009-10 season.

The CDC Thursday revealed that 109 people in the U.S. had been infected with the 2009 H1N1 Influenza A virus, which U.S. and world health officials are now avoiding calling swine flu because the term has caused some people to wrongly assume the disease can be acquired from eating pork products or from coming in direct contact with pigs.

Besser said Thursday that the virus has spread to 11 states, with South Carolina being the most recent state to report 10 new cases.

Even an Obama administration aide and some of his family members were being tested for the virus, White House spokesman Robert Gibbs revealed Thursday afternoon.

The World Health Organization (WHO) also increased its count Thursday to 257 laboratory-confirmed cases in 11 countries, with many of the new reports being attributed to researchers catching up with a backlog of specimens in Mexico.

Besser said the daily rise in the numbers of those infected with the H1N1 flu virus is less important than the new regions where the disease is emerging and whether the virus is mutating.

He said it was too early to know the virulence of the virus and whether those affected now in the U.S. with the milder strain could be protected from a more virulent H1N1 strain in the future.

Besser noted that up until Wednesday, the CDC was the only place in the U.S. where testing for the new strain of the H1N1 virus could be done.

But he said the agency was now rolling out testing capability to every state. "The reason we are able to do that is there has been a major investment over the past five years in state laboratory capability," he said.

Several firms have been rushing to develop diagnostic tests for the H1N1 virus since the government first revealed the infection had pandemic potential.

Sunnyvale, Calif.-based Arrayit Corp. said Thursday it was developing a microarray-based diagnostic test to detect the 2009 H1N1 influenza A virus, which the company said would allow researchers and clinicians to detect the presence of the virus in infected patients and livestock and to distinguish the threatening mutated strain from less harmful variants in humans and swine. Arrayit said it plans to begin mass production of its test kits over the next several weeks. The firm said the test kits will be sent to the CDC for validation and then sold for emergency use by licensed clinics, laboratories and other health care organizations worldwide.

The U.S. has 50 million treatment courses of Tamiflu (oseltamivir) and Relenza (zanamivir) stockpiled. The federal government plans to ship 25 percent of those stockpiled drugs out to states, Besser said, adding that deployment of the antivirals already has been completed in nine states, with all states expected to have the supplies by May 3.

WHO Assistant Director-General Keiji Fukuda said Thursday that his organization has started shipping a portion of its stockpile of 5 million treatment courses of Tamiflu to Mexico and other developing nations.

He noted that Roche AG earlier this week had said it was scaling up the production of the antiviral to meet potential worldwide demands of the drug. Foster City, Calif.-based Gilead Sciences Inc. developed Tamiflu and receives royalties from Roche on sales of the product.

As far as production of a vaccine goes, the CDC has so far shared its material with an academic institution to allow its researchers to work on reference strain and later a seed strain, officials said.

"You grow up the seed stock to a certain level and then you do pilot testing and then you look to make sure that what you have hasn't changed at all and then that is able to move forward to a production phase," Besser said during the news conference.

Acting FDA Commissioner Joshua Sharfstein told lawmakers Thursday the FDA already has begun work on reagents that will be needed to help manufacturers produce and test a vaccine. The agency also is working with WHO and CDC researchers on studies that may determine how well, if at all, the seasonal flu vaccine protects against the 2009 H1N1 influenza A virus, Sharfstein said.

There currently are six approved manufacturers of seasonal influenza vaccines for use in the U.S.: CSL Ltd., GlaxoSmithKline plc, ID Biomedical Corp. of Quebec, MedImmune Inc., Novartis Vaccine, and Sanofi Pasteur Inc. Sanofi also is approved to manufacturer a vaccine against the H5N1 avian flu virus.

While the government works on growing up its seed strain for manufacturing a potential vaccine, Mark Backer, CEO of San Francisco-based Vaxart Inc. said his company does not need to wait with its approach. Vaxart is developing an oral vaccine using a non-replicating adenovirus vector with a local-acting adjuvant.

The firm can use the CDC's gene sequence information to synthesize a physical gene, he said.

"This is a great advantage of our approach and a big part of our ability to move very quickly in response to a new outbreak," Backer said.

The company expects to start its first animal tests by late May, he noted.

Other firms with newer technologies, like Rockville, Md.-based Novavax Inc., which is developing vaccines using virus-like particle technologies, also may be able to help the government develop a vaccine quicker than the traditional egg-based process.

What is unclear now, though, said Besser, is if a vaccine for the new H1N1 strain currently sweeping across the globe is warranted.

"It is too early to know," he said.

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