Safety, immunogenicity and efficacy of modified vaccinia Ankara (MVA) against Dryvax® challenge in vaccinia-naïve and vaccinia-immune individuals

Modified vaccinia Ankara (MVA) was evaluated as an alternative to Dryvax® in vaccinia-naïve and vaccinia-immune adult volunteers. Subjects received intramuscular MVA or placebo followed by Dryvax® challenge at 3 months. Two or more doses of MVA prior to Dryvax® reduced severity of lesion formation, decreased magnitude and duration of viral shedding, and augmented post-Dryvax® vaccinia-specific CD8+ T cell responses and extracellular enveloped virus protein-specific antibody responses. MVA vaccination is safe and immunogenic and improves the safety and immunogenicity of subsequent Dryvax® vaccination supporting the potential for using MVA as a vaccine in the general population to improve immunity to orthopoxviruses.