At least 3.4 million doses of swine flu vaccine will become available the first week in October, the U.S. Centers for Disease Control and Prevention announced today.
In one sense, the news is a setback, as the U.S. government had hoped to receive the first batches of vaccine to help the highest risk groups in September. But CDC officials were upbeat about the late delivery of even this small amount of vaccine, and stressed that plans remain on track to receive much larger batches of product for mass vaccination campaigns starting 15 October.
The first 3.4 million doses contain a live, attenuated version of the novel H1N1 virus causing the pandemic. By the end of the year, CDC anticipates receiving a total of 195 million doses of swine flu vaccine, most of which will contain an inactivated version of the virus.
Jay Butler, chief of CDC’s 2009 H1N1 Vaccine Task Force, explained that the government will distribute the first doses of vaccine to states based on their populations, and each locale and individual providers will determine who receives the first doses. Although in July, the CDC’s Advisory Committee on Immunization Practices spelled out the populations that should have first priority for the vaccine if limited supplies exist, that group totals 42 million—meaning demand will likely far outstrip supply in early October. “There’s not a recommendation for sub-prioritization,” said Butler.
Another complication is that the live virus vaccine that will arrive first is not recommended for pregnant women or children under 2 years of age, two groups considered at high risk. (In pregnant women, the live virus may harm the fetus, and children under 2 had more severe reactions during clinical trials of attenuated vaccine made with seasonal influenza strains.)
Although five manufacturers are racing to supply the U.S. government with vaccine for everyone who wants it, several flu epidemiologists fear that the bulk of product will arrive too late to help many people in the country. As Daniel Jernigan, deputy director of CDC’s influenza division, explained at a press conference today, the novel H1N1 virus currently is in all 50 states, and widespread in 21 of them. “It’s a very strange thing to see that amount of influenza this time of year,” said Jernigan.
The U.S. government had hoped to receive “several tens of millions of doses” of vaccine in mid-September (pdf) to protect people in the highest risk group, but production delays have slowed its delivery. Specifically, companies had difficulty developing a potency assay that measures the 15 micrograms of the viral antigens needed for each dose. (The manufacturing of the live vaccine, which will make up only 12.8 million of the 195 million doses, did not face this problem.) About 40 million doses of vaccine are expected to arrive 15 October, and then manufacturers hope to deliver about 20 million doses each week until the end of the year.