US seeks stockpile of safer smallpox vaccine

Editor's note: This story was revised Aug 17 to add information on funding and a link to the government's request for proposals to supply the vaccine.

Aug 16, 2005 (CIDRAP News) – The US government has called for proposals to supply up to 80 million doses of a weakened smallpox vaccine to protect people for whom the conventional vaccine is too risky, according to two vaccine manufacturers.

Acambis and Bavarian Nordic said the Department of Health and Human Services (HHS) has requested proposals to supply the attenuated vaccine called modified vaccinia Ankara, or MVA. Both companies have developed versions of MVA.

The vaccine is intended for use in people who face an increased risk of serious reactions to the conventional vaccine, such as children, pregnant women, and people with immune system disorders or eczema. The federal government has stockpiled hundreds of millions of doses of the conventional vaccine over the past few years.

Peter Wulff, president and CEO of Copenhagen-based Bavarian Nordic, said in a news release, "With this tender, the US government has committed itself to protect the 25% of the population who cannot safely be given current smallpox vaccines. The world market for a safe smallpox vaccine has now been opened, since governmental authorities in the larger European countries will naturally undertake a similar commitment as the American authorities."

HHS wants to obtain 20 million doses of MVA within 2 years after awarding a contract and to have an option to buy another 60 million doses in the future, according to a news release from Acambis, based in the United Kingdom. The HHS is also calling for vaccine suppliers to conduct clinical trials and obtain a federal license for their vaccine.

Federal officials have set a Sep 29 deadline for receiving company proposals and plan to award one or more contracts in February 2006, according to Acambis and Bavarian Nordic.

Both companies have been developing their versions of MVA under contracts awarded by the National Institute of Allergy and Infectious Diseases in February 2003 and September 2004. Acambis's vaccine is called MVA3000, and Bavarian Nordic's is Imvamune.

The earlier contracts required the companies to test the vaccines in animals, begin clinical trials, and develop plans for mass production. Acambis is collaborating with Baxter Healthcare to manufacture MVA3000.

Acambis said it launched a phase 2 clinical trial of MVA3000 in 700 healthy adults last month. A phase 1 study yielded good results for safety and immunogenicity, with 97% of subjects who were vaccinated at the highest dose showing antibodies specific to the vaccinia virus, the company said.

Existing smallpox vaccines are made with live vaccinia virus, which in rare cases can cause serious or life-threatening side effects such as a severe rash or encephalitis. MVA is a strain of vaccinia that cannot replicate inside human cells and cause a spreading infection, according to HHS.

The MVA contracts will be funded under Project Bioshield, a program enacted last year to support the development of medical defenses against biological, chemical, and radiological weapons, according to Marc Wolfson, spokesman for the HHS Office of Public Health Emergency Preparedness in Washington DC.

Wolfson said he couldn't give an estimate of the cost of the MVA vaccine stockpile. But a Reuters report said investment analysts estimated that the full 80 million doses could be worth more than $1.2 billion.