Health and Human Services Secretary Tommy Thompson said the new doses would be combined with existing supplies and an earlier Acambis contract to create a stockpile big enough to vaccinate every American if needed because of a bioterrorist attack using the smallpox virus.
"The risk is low," Thompson said. "(But) the risk does exist and we must be prepared. We expect to have the doses in hand by the companies by sometime early to late fall next year."
Acambis and Baxter will produce the smallpox vaccine using a purified strain of vaccinia virus grown in live tissue culture. Vaccinia virus is related to smallpox and stimulates immunity to the smallpox virus.
The HHS plan for the nation's public health system to use during a smallpox outbreak, the "Interim Smallpox Response Plan and Guideline," released Monday, is called ring vaccination or search and containment.
The key is early identification of individuals suspected of smallpox exposure and then quickly vaccinating the ring of people with whom those first few had contact.
From there, additional outward rings of contact would be established based on who the initial ring of people had been in contact with until basically the initial smallpox victims are surrounded by a barrier of immunized people, preventing the spread of the virus.
Acambis beat out two giants in the pharmaceutical industry, Merck & Co. and GlaxoSmithKline, despite those companies' experience in vaccine production. The cost per dose from Acambis, at $2.76, and the delivery date of no later than the end of 2002, beat out offers from both competitors, Thompson said.
Some 15.4 million doses of the "Dryvax" smallpox vaccine have been in storage since production ended in 1983, following the eradication of smallpox in the 1970s. Researchers at the National Institutes of Health are testing diluted vaccine -- at a ratio of 1 to 5 -- to expand the supply, which would create 77 million doses.
In September 2000 the Centers for Disease Control and Prevention in Atlanta awarded Acambis a contract to produce a new supply of 40 million doses of smallpox vaccine by 2004. This contract was amended in September 2001 to 54 million doses with delivery by 2002.
Thompson said by combing the new 155 million doses, with the 54 million already coming from Acambis, and the expected 77 million diluted doses, there will be 286 million doses of smallpox vaccine, enough for everyone in the country.
The $79 million existing Acambis contract, along with the $428 million new contract, brings the total to just a couple of million dollars less than the $509 million appropriated for the project in the supplemental appropriations bill signed by President Bush.
The diluted doses remain a question mark, however, as the NIH is not expected to finish potency studies at the 5-to-1 ratio until spring.
Dr. Anthony Fauci of NIH said, however, the "take rate" of the vaccine in initial studies was so good, "I would be very surprised if we weren't able to have the dilution available to us."
Thompson said one plus of going with Acambis was the company already has done much of the research and development on the vaccine and can gear up to deliver the doses two years sooner than its original contract stipulates. Production could begin in December.
That does not mean, however, there will be any shortcuts in the required Food and Drug Administration approval process for the vaccine.
Dr. Murray Lumpkin, director of FDA's Center for Drug Evaluation and Research, said the smallpox vaccine "clearly meets our standards for a priority review" -- given to other drugs needed for life-threatening illnesses. He offered Acambis the option of a "rolling review" where FDA looks at clinical testing data as it is finished so when human trials are complete, the review is almost ready as well.
But Lumpkin said there will be full clinical trials -- included in the negotiated cost of the contract -- and that "there are going to be no regulatory shortcuts."
Cambridge, England-based Acambis issued a statement Wednesday that said both it and Baxter would contribute to the manufacturing process, with first clinical trials coming in early 2002.
Chief Executive Officer Dr. John Brown said: "The progress we have already made on our existing contract makes us ideally placed to deliver the U.S. government's requirements under this new contract."
When it comes to administering the vaccine Thompson said there would be no discrimination based on citizen status, race, sex or anything else should a smallpox outbreak occur.
All of the officials concurred that just because there were three lines of the vaccine, the new doses in the Acambis contracts, the stored full potency doses and any diluted doses, did not mean there would be any discrimination in who would get which type of vaccine dose.
The decision will be made on how many doses are available at the time it is needed, they said, indicating the newest vaccine would be used first and the diluted vaccine only if necessary because of the size of the outbreak.
Thompson also said Acambis also has agreed to provide the vaccine to other countries, such as Canada, Great Britain, France, Germany and Mexico, either as an extension of the U.S. contract or by negotiating a separate deal.