Viral vector vaccines utilize viruses as a delivery mechanism for DNA into target cells in order to protect against disease. The delivered DNA is transcribed by the host cell in order to produce proteins or antigens which result in an immune system response. Viral vector vaccines were first developed in 1972 using a genetically modified SV40 virus, and many new types have been invented since. As of 2021, six viral vector vaccines were approved for use in humans.
