Dec. 23 (Bloomberg)
http://www.bloomberg.com/apps/news?pid=20601102&sid=ahaLdhKkNE0c
 
– AstraZeneca Plc recalled 4.7 million doses of its nasal spray version of the swine flu vaccine after routine tests showed a decline in potency, U.S. regulators said.

The doses remain safe, and people who have already been inoculated don’t need to get vaccinated again, said Norman Baylor, director of vaccines research and review for the U.S. Food and Drug Administration. About 3,000 of the affected doses remain in warehouses, and AstraZeneca will send recall notices to clinics that may have unused vials of the vaccine.

The recall follows a similar move on Dec. 15 by Paris-based Sanofi-Aventis SA, which recalled 800,000 swine flu shots. Manufacturers maintain samples for testing from each vaccine lot that is shipped, and they continue to test them for waning potency, Baylor said. Both recalls were made voluntarily after the strength dropped below pre-specified thresholds.

“There are no safety concerns with these lots,” Baylor said in a conference call with reporters yesterday. “We do see a decline in potency every now and then.”

The doses were distributed in October and early November, and the “vast majority” have already been administered, said Tor Constantino, a spokesman for London-based AstraZeneca, in a telephone interview yesterday. The doses passed all potency tests before the vaccines were shipped. The company has never seen a similar potency decline with its seasonal-flu version of the FluMist nasal spray vaccine, he said.

60 Million Vaccinated

At least 60 million people in the U.S. have received one of several kinds of swine flu vaccine, out of 111 million doses available as of this week, the U.S. Centers for Disease Control and Prevention reported yesterday. After initially limited supplies, most states are now offering free inoculations to anyone who wants one, said Anne Schuchat, head of the CDC’s National Center for Immunization and Respiratory Diseases, on a conference call.

AstraZeneca has shipped 23 million doses out of its contract for 40 million with the U.S. Health and Human Services Department, Constantino said. The U.S. ordered 251 million doses of swine flu vaccine from five companies, and most states now have enough to offer the vaccine to people of all ages. The shots and nasal sprays are paid for by the U.S. government, though clinics can charge a fee to administer them.

Vaccine availability across the country has been rising, even as illnesses are on the wane, according to the CDC. Swine flu rates have fallen for seven straight weeks and are at their lowest level since pupils returned to classes in September.

Clinging Antigen

Sanofi’s decreased vaccine potency may have been due to the key ingredient, antigen, clinging to the wall of the syringe over time, the CDC’s Schuchat said after the recall.

AstraZeneca’s vaccine has a different type of applicator and is made using a different process, the FDA’s Baylor said. Scientists are still trying to determine what was responsible for the reduced potency. Such decreases are rare but not unheard of, he said. A batch of seasonal flu vaccine was recalled for the same reason in February, FDA spokeswoman Karen Riley said in yesterday’s conference call.

H1N1 infected 50 million people in the U.S. and killed an estimated 10,000 through Nov. 14 from the start of the pandemic in April, according to CDC estimates reported Dec. 10. About 36,000 people die each year in the U.S. from influenza.

Most swine flu infections are no worse than seasonal flu, according to CDC officials. In rare cases the disease leads to severe illness and death in otherwise health people. Unlike seasonal flu, swine flu disproportionately attacks the young. In a typical flu season, 90 percent of deaths are over age 65; with swine flu, the effects are reversed, with 90 percent of deaths under age 65.

((To search by zip code for flu clinics with available vaccines, go to http://www.flu.gov))

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