Oral poliovirus vaccine (OPV), comprising live attenuated viruses, can reduce the incidence of other infections. Albert Sabin, who developed an OPV, administers the vaccine, 1966.
PHOTO: PHOTO12/UNIVERSAL IMAGES GROUP VIA GETTY IMAGES
Prophylactic vaccination is the most effective intervention to protect against infectious diseases. The commonly accepted paradigm is that immunization with both attenuated virus (live but with substantially reduced virulence) and inactivated (killed virus particles) vaccines induces adaptive and generally long-term and specific immunity in the form of neutralizing antibodies and/or activating pathogen-specific cellular immune responses. However, an increasing body of evidence suggests that live attenuated vaccines can also induce broader protection against unrelated pathogens likely by inducing interferon and other innate immunity mechanisms that are yet to be identified.