The last naturally occurring case of smallpox was reported in 1977. In 1980, the World Health Organization declared that smallpox had been eradicated. The Dryvax vaccine was used in smallpox eradication, and the United States has enough of its successor, Acam2000, available to vaccinate the population in the case of a terrorist attack. Prior to availability of Acam2000, a NIAID-supported clinical trial that found that Dryvax could successfully be diluted up to five times and retain its effectiveness. These findings helped expand the number of individuals Dryvax could protect until sufficient doses of Acam2000 were made for the entire U.S. population.
People with weakened immune systems or skin conditions, such as atopic dermatitis, or eczema, are at increased risk for serious side effects from Dryvax and Acam2000. NIAID is pursuing the development of new, safer smallpox vaccines that could be used to protect these groups. One of the most promising is being developed by the biotechnology company Bavarian Nordic and uses a vaccine platform technology known as Modified Vaccinia Ankara – Bavarian Nordic (MVA-BN). NIAID supported early advanced development work for this important vaccine, with initial efforts largely focused on the liquid formulation. NIAID support spanned preclinical evaluation through Phase II clinical trials. The trials assessed the vaccine in healthy participants, HIV-positive volunteers, and people with atopic dermatitis or a history of atopic dermatitis. These studies evaluated factors such as safety, immunogenicity, duration of protection, and route of vaccination. The vaccine was transitioned to the Biomedical Advanced Research and Development Authority (BARDA) for advanced development. In 2013, Canada and the European Union approved the vaccine (under the trade names IMVAMUNE and IMVANEX) for use in the general population, including people with weakened immune systems or atopic dermatitis. As of August 2014, 24 million doses were delivered to the U.S. Strategic National Stockpile (SNS) for use among these groups.
NIAID also supported a project to develop a freeze-dried, or lyophilized, version of the vaccine. Compared to the current liquid formulation, the lyophilized version is more stable with a longer shelf life. NIAID has transitioned this project to the U.S. Department of Health and Human Services Biomedical Advanced Research and Development Authority (BARDA) for further development.
NIAID is supporting studies to identify adjuvants that can be used to decrease the number of vaccinations needed to provide protection and explore MVA as a platform technology to provide protection against more than one disease.