FDA OKs Flu Vaccines for 2008-09 Season

For strains of influenza A (H3N2) -- the most prevalent virus during the 2007-08 season, the vaccine was only 58 percent effective. And it was 100 percent ineffective against influenza B infections, leaving an overall vaccine success rate of about 44 percent, according to the U.S. Centers for Disease Control and Prevention.

Despite that 44 percent rate, it has been higher in some years and lower in others, Dr. Dan Jernigan, deputy director of CDC's Influenza Division, said during an April 17 teleconference. "In the last 20 seasons, 16 have had good matches, and there have been four that were less than optimal matches," he said.

---

---

Even if the vaccines and the circulating strains aren't an exact match, they will provide some protection and may reduce the severity of the illness or prevent flu-related complications, officials said.

A study published in the April 17 issue of Science could eliminate much of the guesswork, however. Researchers reported that flu viruses originate in East Asia and Southeast Asia, and it takes about eight to nine months before these new viruses reach western Europe and North America.

Jernigan said last spring that the CDC was involved in promoting better surveillance of emerging flu viruses in East Asia and Southeast Asia. The hope is that these surveillance efforts will lead to more effective and better-matched vaccines.

According to the CDC, each year from 5 percent to 20 percent of the U.S. population gets the flu. More than 200,000 people are hospitalized from flu complications, and about 36,000 people die from the disease. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications.

More information

To learn more about the flu, visit the U.S. Centers for Disease Control and Prevention.