[5] This third-generation smallpox vaccine has the advantage that it cannot reproduce complete virions in human cells, "the block of the MVA life cycle occurs at the step of virion assembly resulting in assembly of immature virus particles that are not released from the infected cell.
"[5] By inserting antigen genes into its genome, modified vaccinia Ankara virus is also used as an experimental viral vector for vaccines against non-poxvirus diseases.
It was produced by more than 500 serial passages of vaccinia virus (from a wild strain discovered by the Turkish vaccine institute of Ankara) in chicken embryo fibroblasts.
[14] Modified vaccinia Ankara strains engineered to express foreign genes are vectors for production of recombinant proteins, the most common being a vaccine delivery system for antigens.
[20] A US Centers for Disease Control and Prevention (CDC) analysis of the vaccination status of 5402 individuals who had mpox infections during the summer of 2022 showed that unvaccinated people appeared to be 14 times more likely to be infected than those with a single (of two recommended) doses; the results were noted to be admittedly preliminary.