500,000 Doses of Attenuated Smallpox Vaccine Delivered to USG
By Luciana L. Borio, M.D., December 7, 2005
In September 2004, the vaccine manufacturing company Acambis was awarded a contract by the National Institute of Allergy and Infectious Disease (NIAID) to develop and manufacture a modified Vaccinia Ankara (MVA) smallpox vaccine. Last week, Acambis announced the delivery of 500,000 doses of the investigational MVA3000 attenuated smallpox vaccine which it developed with Baxter Healthcare SA.
MVA is a live, non-replicating form of vaccinia. Although it has never been used in the field to control a smallpox outbreak, laboratory data indicate that in adults MVA induces antibody responses comparable to those produced by live New York City Board of Health (NYCBH) strain vaccines, and in animal studies, it is protective against a range of orthopoxviruses, including monkeypox.
Currently available smallpox vaccines in the U.S. are made from live, replicating vaccinia virus (NYCBH). They include DryVax (Wyeth), WetVax (Aventis), and the newly produced ACAM2000 (Acambis). The latter was produced in cell culture, whereas the others were produced in calves. Of the three, DryVax is the only licensed vaccine, and it is now used to vaccinate selected military personnel and workers in poxviruses laboratories. When smallpox was endemic, DryVax and WetVax were successfully used in controlling outbreaks.
While preferred, the NYCBH strain vaccines are contraindicated for those who are severely immunosuppressed or have a history of eczema or other severe exfoliative skin disorders. When the military recently vaccinated 730,000 personnel and the CDC and health departments vaccinated 38,000 workers, very few adverse advents were reported [1,2]. However, given the risk to certain populations, an even less reactogenic vaccine is desirable. It has been estimated that there are 10 million persons in the U.S. who may be immunocompromised, including 8.5 million cancer patients and survivors, 850,000 people with HIV infection and 184,000 transplantation patients .
In August of this year, the U.S. Department of Health and Human Services (DHHS) issued a Request for Proposals (RFP) for “the manufacture of up to 20 million doses of MVA attenuated smallpox vaccine and advanced clinical testing up to and including obtaining a product license for MVA.” Award of a contract is expected in February 2006.
Vellozzi C et al. Generalized vaccinia, progressive vaccinia, and eczema vaccinatum are rare following smallpox (vaccinia) vaccination: United States surveillance, 2003. Clin Infect Dis. 2005 Sep 1;41:689-97.
Poland GA et al. The U.S. smallpox vaccination program: a review of a large modern era smallpox vaccination implementation program. Vaccine. 2005 Mar 18;23:2078-81.
Kemper AR et al. Expected adverse events in a mass smallpox vaccination campaign. Eff Clin Pract. 2002 Mar-Apr;5:84-90.
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