THURSDAY, Aug. 20, 2009 (HealthDay News) -- Health experts do not believe that the delay in receiving swine flu vaccine will thwart the U.S. government's strategy to protect Americans against the newly circulating virus.
But having only 45 million doses on hand by Oct. 15, rather than the originally anticipated 120 million doses, does throw a slight wrench into plans to vaccinate those who might need the shots the most.
"The vaccine undoubtedly will still be useful," said Dr. John Treanor, professor of medicine and of microbiology and immunology at the University of Rochester Medical Center in New York. "It may not be as useful than if it were ready in September, but I think it will still be useful."
Added Dr. Kenneth Bromberg, director of the Vaccine Research Center at The Brooklyn Hospital Center in New York City: "The best weapon we have is the vaccine and the sooner it is available, the more useful it will be. If the flu comes later, [the delay] will be less relevant. If the flu comes earlier, it will be more of a problem."
According to federal health authorities, after mid-October, 20 million more doses of the vaccine will be shipped each week.
In a way, the delay is no surprise, given the unpredictability of influenza in general and the elaborate and fragile requirements of the vaccine production process.
"We know that making a flu vaccine is a committed process. There are many steps in that process and all it takes is for something to be a little bit off on one of the steps and you're going to see delays or shortages," Treanor said.
The main problem right now is that manufacturers are simply not getting the yield of vaccine they had expected.
"The delay is being attributed to slower and wimpier growth of the vaccine substrate used to make the vaccine. The amount vaccine manufacturers are getting out of millions of eggs is less than expected, and it's taking longer to make," Treanor explained.
The government has shipped off new "seed strains" of the H1N1 virus to help speed up production, according to the Associated Press.
Another factor contributing to the delay is not having enough manufacturers to actually package the vaccine, the wire service reported.
But that problem is fixable, partly by new efforts being made by the government to recruit more companies for the packaging effort.
"Delays that involve the inability to grow the vaccine you can never get around, whereas having delays in filling syringes or filling vials, something can be done," Bromberg said. "We have more leeway to work with that. That's less of a problem than if the stuff didn't exist."
Another expert noted that the original estimates of how much vaccine could be made by October might have been too high.
"This slow-down is not unexpected. We feel that some of the earlier projections that were made by pharmaceutical companies were a bit optimistic," said Dr. Ciro Sumaya, a professor at Texas A&M Health Science Center School of Rural Public Health and a member of the U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices. "We are following closely the supply available, as it has a lot of implications for how one is going to recommend giving the vaccine. Prioritization in giving to various groups will depend on the availability, so it's going to be a very fluid, very dynamic look at recommendations."
Federal officials have said there will be enough vaccine to immunize priority groups, which include pregnant women, public health workers and small children.
According to the U.S. Centers for Disease Control and Prevention, these groups total about 160 million individuals.
"If there is less vaccine, the roll-out may be done at a local level," Bromberg said. "I don't think the same amount of vaccine is going to be available in every place, but I assume that health-care workers who can spread the flu at an institution will get vaccinated first pretty much no matter what, as well as high-risk people."
Other good news is that, so far, the outbreak of swine flu in the southern hemisphere is exactly the same as it was in the northern hemisphere in the spring, Treanor said. "When it comes back it will likely be similar," meaning relatively mild, he noted.
"So far, this doesn't appear to be the swine flu of 1918," Bromberg added. That outbreak infected about one-third of the world's population or some 500 million people, killing an estimated 50 million.
Visit the U.S. Centers for Disease Control and Prevention for more on swine flu.