Government health officials said on Monday that the United States will have barely more than a third of the 120 million doses of swine flu they hoped would be available by mid-October. That's far less than the 160 million doses they originally predicted in July.
Bill Hall, spokesman for the U.S. Department of Health and Human Services, said that despite the projection that only 45 million doses will be available at the start of the mass vaccination campaign scheduled to start in October, there would still be enough vaccine available to achieve the primary goal of vaccinating the groups most in need, including pregnant women; children under four years old and public health workers. . "Our priority groups for vaccination have not changed," he said. "We still have enough vaccine to cover the priority groups identified."
Hall added that even after the first wave of the vaccine is made available, manufacturers will continue to churn out 20 million doses each week.
"Early on, there were issues with production yield, but that has improved significantly over the past several weeks," Hall said. He noted that other confounding factors, such as one company finishing production of its regular seasonal flu vaccine behind schedule, further slowed the production of the swine flu vaccine.
Still, Monday's revelation comes amid warnings from infectious disease experts of a fall resurgence of the pandemic strain of the H1N1 virus. And Hall said the results of the tests that will determine whether one or two doses of the vaccine are necessary to prevent sickness have not yet yielded results.
Dr. William Schaffner, chairman of the Department of Preventive Medicine at Vanderbilt University in Nashville, Tenn., said that the latest status report is troubling news.
"We've been in a race to try and get this vaccine manufactured," he told ABC News' Diane Sawyer on "Good morning America" on Tuesday. "It makes us all a little bit nervous.
"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."
Last week, the U.S. Centers for Disease Control and Prevention said that since the swine flu appeared roughly four months ago, it has sent 7,511 Americans to the hospital and killed 477.
Disease specialists have pointed out that despite these numbers the impact of the swine flu has been relatively mild. And Hall said that the anticipated shortfall in the vaccine supply was not completely unanticipated – a statement with which influenza experts agreed.
"A lot of things go into the making of a flu vaccine, which is a complex, multi-step process," said Dr. John Treanor, professor of Medicine, Microbiology and Immunology at the University of Rochester Medical Center in Rochester, N.Y. " I actually think it is amazing that 45 million doses will be ready by October; after all, the virus wasn't even recognized until the end of April."
Dr. Peter Katona, associate clinical professor of infectious diseases at the David Geffen School of Medicine at UCLA, said the shortfall "is in no way surprising" considering the many steps in the vaccine-making process that are prone to delay and other problems. Among these, he said, are the fact that normal vaccine production can be interrupted by a problem in a single plant, that the egg-based system of vaccine production is inefficient and archaic, and that the production of the swine flu vaccine coincides with the production schedule of the regular seasonal flu vaccine.
"In other words, a lot of things can go wrong," he said, "and the government doesn't have a great track record for predictions."
Still, the impact of the shortfall on vaccination efforts remains to be seen. Dr. Amir Afkhami Assistant Professor and Associate Director of Residency Training at the George Washington University School of Public Health and Health Services said any vaccine shortage that does arise will underscore the need to get the vaccine to those who need it the most.
"The impact of limited vaccine stocks will be that providers will need to prioritize vaccine delivery to immunization priority groups which are considered more vulnerable to the virus," he said.
He said that these groups includes pregnant women; those who come in close, daily contact with children under six months old; public health workers; all children between the ages of six months and 4 years old; and children ages 5-18 who have chronic medical conditions.
As for everyone else, Schaffner said that the public would do well to ensure that they at least adhere to recommendations on the seasonal flu vaccine.
"The regular flu shot will be available by the end of the month or beginning of September in doctor's offices, clinics, pharmacies," he said. "Everybody should go ahead and get themselves vaccinated against that."