Nov. 11 (Bloomberg) -- Sanofi-Aventis SA will have shipped 20 million doses of the swine flu vaccine for use in the U.S. by the end of the week, said Chris Viehbacher, the company’s chief executive officer.

The Paris-based drugmaker will meet its goal of supplying the U.S. with 75 million doses of the vaccine for swine flu, or H1N1 influenza, by year-end, Viehbacher said today at a briefing at the company’s Sanofi Pasteur vaccine unit in Swiftwater, Pennsylvania.

Swine flu may have infected as many as 5.7 million people from April through July in an initial wave of the virus that swept the U.S. The outbreak is at its highest levels yet, responsible for almost 8 percent of doctor visits, according to the U.S. Centers for Disease Control and Prevention’s Web site.

“For us, there is no delay,” Viehbacher said.

Sanofi has delivered more shots than any of other supplier, responsible for about one-third of the doses received for U.S. use, according to the Food and Drug Administration Web site. About 38 million doses were available for states to ship to local hospitals, clinics and physicians as of Nov. 6, according to the CDC, which is based in Atlanta.

Sanofi was one of five companies the U.S. contracted with for the swine flu vaccine in June. The U.S. initially ordered 30 million doses and later increased its contract with Sanofi to 75 million of the total 251 million supply.

Cultivating Vaccine

Vaccine makers have found it difficult to cultivate the quantities of virus necessary for an H1N1 vaccine. The initial strain yielded 50 percent to 75 percent less antigen compared with a typical seasonal flu strain, according to the World Health Organization. The virus didn’t initially grow well in eggs, the principal medium used by the industry, vaccine makers said. Antigen is the substance that induces immunity.

Sanofi initially anticipated the yield to be 50 percent of historic levels. Now the company is ahead of its projections at 80 percent of historic yields, Wayne Pisano, president and chief executive officer of Sanofi Pasteur, said Oct. 30.

Sanofi produces more than 1.6 billion vaccine doses against 20 diseases every year, enough to immunize more than 500 million people, according to the company’s Web site. Its 500-acre vaccine production facility in Swiftwater is running 24 hours a day, according to the company.

To contact the reporter on this story: Tom Randall in New York at trandall6@bloomberg.net

Last Updated: November 11, 2009 15:22 EST