Initial production problems mean that only about one-third of the expected 120 million swine flu vaccine doses will be available in the United States by mid-October, federal health officials said Monday.
Even so, there will still be enough to vaccinate people in priority groups such as public health workers, pregnant women, and children under 4 years old, officials said.
"Our priority groups for vaccination have not changed," U.S. Department of Health and Human Services spokesman Bill Hall told ABC News. "We still have enough vaccine to cover the priority groups identified."
After the first batch of swine flu vaccine is made available for the start of the mass vaccination campaign in October, manufacturers will continue to produce 20 million doses a week, Hall added.
"Early on, there were issues with production yield, but that has improved significantly over the past several weeks," he told ABC News. Other factors that further slowed swine flu vaccine production have also been resolved, he said.
The news that there will be far fewer than expected swine flu vaccine doses available in October "makes us all a little bit nervous," said Dr. William Schaffner, chairman of the Department of Preventive Medicine at Vanderbilt University in Nashville.
"We won't have as much vaccine to start a vaccine program, and we're worried that we will have people sick that could have been prevented and people in the hospital that could have been prevented," he said Tuesday on Good Morning America.