Non-replicating smallpox vaccine
MVA-BN is approved in Canada (marketed under the trade name IMVAMUNE®) and in the European Union (marketed under the trade name IMVANEX®. Phase 3 registration trials have been successfully concluded in the U.S. and a BLA was filed with the FDA in October 2018.
MVA-BN is a non-replicating smallpox vaccine distributed in liquid-frozen formulation, suitable for use in people for whom replicating smallpox vaccines are contraindicated (e.g. people with HIV and atopic dermatitis). The vaccine is the only non-replicating smallpox vaccine approved in Europe for use in the general adult population. Although not yet approved in the United States, MVA-BN is currently stockpiled by the U.S. Government for emergency use in people for whom replicating smallpox vaccines are contraindicated. Registration studies to support FDA approval for use of the vaccine in the entire population have been concluded and a BLA was submitted in October 2018.
Traditional smallpox vaccines are based on replicating vaccinia virus strains. Although these vaccines have been effective in preventing the disease, their use may be associated with an increased risk of adverse events, including death and severe disability.
MVA-BN is injected like other modern vaccines rather than pricked into the skin with a bifurcated needle. While the MVA-BN virus is highly attenuated and is thus incapable of replicating in the body, it is still capable of eliciting a potent immune response and does so without producing the post-vaccination complications associated with traditional smallpox vaccines.
Although the World Health Organization (WHO) declared smallpox eradicated in 1980, this contagious and deadly disease remains high on the list of possible bioterror threats. Unique to humans, the disease is caused by the Variola virus and transmitted from person to person through direct contact with contaminated fluids and objects, as well as through the air. Historically, about 30% of those who became infected with smallpox died from the illness. There is currently no cure for the disease, vaccination is the only proven protection.
The U.S. government considers smallpox a material threat to national security. National security concerns are based on intelligence regarding previous biological weapons programs, coupled with the infectivity of the virus, an increasingly vulnerable population due to lack of immunity, and the relative ease of large-scale production. In fact, the U.S. Department of Defense has a mandatory smallpox vaccination program for troops being deployed to certain areas around the globe.
While the only known samples of smallpox are held at secure labs in the U.S. and Russia, the U.S. National Research Council found in a 2008 report that "the creation or acquisition of smallpox is well within the technical reach of a determined and well-resourced terrorist."
Given today's global travel and the virus' long incubation period, all nations must safe-guard against this virus. A smallpox outbreak anywhere could quickly become a global, not a local, problem.