U.S. health officials began a search for extra flu vaccines on Wednesday after one of only two major manufacturers, Chiron Corp., lost its entire year’s production to contamination.

A million extra doses were coaxed out of vaccine maker Aventis-Pasteur, Health and Human Services Secretary Tommy Thompson said.

U.S. officials were also speaking to British regulators who revoked Chiron’s flu vaccine license to confirm whether all 48 million doses would be kept off the market.

Chiron’s surprise announcement on Tuesday that British regulators had found widespread problems at its Liverpool vaccine plant meant the United States lost nearly half its anticipated influenza vaccine supply for the 2004-2005 flu season just starting now.

After last year’s unusually early flu season made headlines, vaccine officials had hoped that the normally unenthusiastic U.S. population might actually step up and get vaccinated in large numbers.

Now these officials will have to cajole vaccine providers into sharing their stashes, and convince the U.S. public to save vaccine for those who need it most.

Health and Human Services Secretary Tommy Thompson said the United States now had 55.4 million doses of vaccine on hand or available.

USABLE DOSES

Scientists with the U.S. Food and Drug Administration will meet on Friday with Chiron officials, Thompson told reporters.

It may be possible to find some doses that were not contaminated and that might be usable, he said. However, he cautioned, “It does not look promising at this point.”

The Centers for Disease Control and Prevention was working to find out where vaccines had already been shipped to providers such as clinics, drug stores and employers.

“What we are hoping to do is to map out available vaccine in a way that will help clarify where the most likely areas of shortage will be,” said CDC director Dr. Julie Gerberding. “Keep in mind that vaccine distribution for flu is largely in the private sector. We do not have the authority to require redirection.”

CDC says only high-risk people should now be getting the flu vaccine and that others should wait. Those in the high-risk group include babies aged 6 months to 23 months, people over 65, pregnant women and people with chronic diseases.

Gerberding said the shortage illustrated a chronic problem - a lack of vaccine makers.

“Our entire vaccine production system is fragile in our country. We periodically have vaccine shortages because there are too few manufacturers and too few products,” she said. “We need a comprehensive national strategy with the private sector to develop a manufacturing capacity that doesn’t exist at the moment.”

Although health officials have been warning of shortages for years, experts agreed this was the worst yet. “This catastrophe I think is going to be an impetus to the Congress and the manufacturers to start transforming the way we make vaccines,” Thompson said.

Influenza vaccine takes months to manufacture and has to be made fresh every year based on circulating strains.

Doctors can turn to antiviral drugs, such as Roche’s Tamiflu, amantadine, rimantadine and zanamivir, sold by GlaxoSmithKline under the brand name Relenza. But they are no substitute for vaccination against a disease that kills 36,000 Americans in an average year.