The government is ready to move ahead with ordering significantly more than the 2 million doses it acquired from French vaccine maker Sanofi-Pasteur before testing began earlier this year to jump-start the U.S. vaccine stockpile in case the tests were successful, Dr. Anthony S. Fauci said Sunday.
Additional tests of the vaccine are being conducted on the elderly and children, said Fauci, director of the National Institute of Allergy and Infectious Diseases.
Preliminary data from the first 115 of the initial tests on 450 healthy adults showed an immune response that scientists believe is strong enough to protect against the avian influenza that's spreading among birds in Asia and Russia. Fauci said he expects analysis of data from the other 300 tests will show similar results.
"We're now, given these results, going to move ahead with ordering from the company additional doses," he told The Associated Press in a telephone interview.
"I can't tell you exactly how many; that's going to depend on the production capability, but certainly it will be significantly more than the 2 million doses."
For the past year, government health officials have been hurrying to develop the vaccine because of fears that the avian influenza strain could change into one that could spread rapidly among humans throughout the world.
While the strain has killed millions of birds, only about 50 humans have died from it and so far there has been no widespread transmission of the virus from one human to another.
Fauci said he thought the Food and Drug Administration could approve the new vaccine fairly quickly because it is similar to other seasonal flu vaccines the agency approves each year. The bigger problem is the lack of manufacturing capacity to produce the number of doses that may be needed.
An influenza pandemic similar to the one in 1918 that killed 50 million people would require hundreds of millions of doses of the vaccine, Fauci said, and the handful of companies that now make influenza vaccines cannot produce the new bird flu vaccine and the regular seasonal flu vaccine at the same time.
Production of next winter's seasonal flu vaccine will end later this month, meaning it will be mid-September at the earliest before mass production of the bird flu vaccine can get under way, he said.
"It's less a regulatory issue than a production capacity issue," Fauci said.
The next step in the testing process is to try out the vaccine on a group of volunteers over age 65, followed by tests on children. Fauci said trials on the over-65 volunteers will begin within a month, and will take four to six months to complete. Tests on children will follow immediately.
In each case, Fauci said, scientists will determine if there are safety issues associated with giving the vaccine to those more vulnerable groups and what the appropriate dosage level should be for each group.