Safer, Fast-Acting Smallpox Vaccine

A new vaccine for smallpox is designed to be safer and to be effective three days after vaccination, compared to traditional vaccines that give protection after 10-14 days.

The biologic mechanism behind traditional replicating smallpox vaccines available today takes time to build up in the body to a level where an immune response can be detected, which takes 10-14 days. The new vaccine, called Imvamune, is a nonreplicating vaccine that can be given at a higher injectable dose, causing a quick immune response. Imvamune is being developed by Bavarian Nordic (Copenhagen, Denmark).

Development of the new vaccine, based on the modified vaccinia Ankara virus, was begun in 1999. Bavarian Nordic has completed two clinical studies of healthy volunteers and has three ongoing studies. One is a study comparing Imvamune to DryVax (a traditional vaccine from Wyeth Laboratories), one is a study of Imvamune in patients with atopic disorders, and the third is a study of Imvamune in patients with HIV. The company expects to begin production of Imvamune in 2005. The company's global partner on the manufacture of the vaccine is GlaxoSmithKline (London, UK).

Bavarian Nordic is participating in an ongoing program by the U.S. government to develop a safe smallpox vaccine based on the modified vaccinia Ankara virus, and has been awarded two contracts under this program. All traditional replicating smallpox vaccines have been associated with severe side effects, such as encephalitis, generalized vaccinia infection, eczema vaccinatum, local progressive vaccina infection, and myo-pericarditis. Because of these, about 25% of the population should not be given current smallpox vaccines: the very young, the elderly, the pregnant, and those who are immune-compromised.

"Based on data from a number of our animal models and clinical trials, Bavarian Nordic expects Imvamune to be effective and to protect against smallpox infection three days after just one vaccination, while traditional replicating vaccines only show protection after 10-14 days,” noted Peter Wulff, president and CEO of Bavarian Nordic.




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