Original antigenic sin, also known as antigenic imprinting, the Hoskins effect,[1]immunological imprinting,[2] or primary addiction[3] is the propensity of the immune system to preferentially use immunological memory based on a previous infection when a second slightly different version of that foreign pathogen (e.g. a virus or bacterium) is encountered. This leaves the immune system "trapped" by the first response it has made to each antigen, and unable to mount potentially more effective responses during subsequent infections. Antibodies or T-cells induced during infections with the first variant of the pathogen are subject to repertoire freeze, a form of original antigenic sin.
^Schiepers, Ariën; van ’t Wout, Marije; et al. (6 September 2022). "Molecular fate-mapping of serum antibodies reveals the effects of antigenic imprinting on repeated immunization". bioRxiv10.1101/2022.08.29.505743.