US government health officials announced plans Monday for a second vaccine to protect people from avian influenza because the virus spreading among birds in Asia, Africa, and Europe is changing. The government has several million doses of an earlier bird-flu vaccine, but it was based on a sample of virus taken from Vietnam in 2004. The germ is believed to have mutated enough since then that the form now circulating in Africa and Europe may be different, health officials said. U.S. Health and Human Services (HHS) Secretary Mike Leavitt said Monday he has authorized the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC) to start work on a second vaccine for humans. "In order to be prepared, we need to continue to develop new vaccines," Leavitt said at an immunization conference in Atlanta, Georgia. Government health experts would not speculate on whether the earlier vaccine would still protect humans. They said only that they believe it would be less effective than a new vaccine based on a more recent virus sample. Health officials plan to base the second vaccine on a sample taken from Indonesia last year. The U.S. government already is spending $250 million for about 8 million doses against the Vietnamese version of bird flu. Federal officials contracted with two companies-Chiron Corporation and Sanofi Pasteur-for those doses, and most already have been produced. The second vaccine must be developed and tested, and HHS had no estimate for the cost of that work. The World Health Organization has reported at least 174 human cases of bird flu, including 94 deaths since 2003. So far, most of the human victims were in very close contact with infected birds, but health officials worry that as bird flu spreads, it could mutate into a strain that easily passes between humans.
