Smallpox and vaccinia
The Smallpox vaccine, using a similar pox virus called Vaccinia, was always as well as being the first vaccine the most intrinsically dangerous commonly used one. When Voltaire reported that 60% of people caught Smallpox, and there was a 1 in 3 mortality among them, and the previous technique if inducing immunity - variolation - had a mortality on the order of 1-2% the balance of risk was favourable.
Current estimates of death rates in widespread Smallpox immunisation are on the order of 1-2 per million, which requires a significant risk of re-introduction to make favourable except for those tasked to deal with it.
The HIV epidemic has brought renewed interest in developing attenuated poxvirus vectors as future HIV vaccines and perhaps the original smallpox vaccination itself actually protected against HIV.
- ↑ Esteban M. Attenuated poxvirus vectors MVA and NYVAC as promising vaccine candidates against HIV/AIDS. Human vaccines. Dec; 5(12):867-71.
- ↑ Weinstein RS, Weinstein MM, Alibek K, Bukrinsky MI, Beda B. Significantly reduced CCR5-tropic HIV-1 replication in vitro in cells from subjects previously immunized with Vaccinia Virus BMC Immunology, 11:23doi:10.1186/1471-2172-11-23