antigenic escape antigenic escape antigenic escape, immune escape, immune evasion or escape mutation occurs when the immune system of a host, especially of a human being, is unable to respond to an infectious agent: the host's immune system is no longer able to recognize and eliminate a pathogen, such as a virus. this process can occur in a number of different ways of both a genetic and an environmental nature. such mechanisms include homologous recombination, and manipulation and resistance of the host's immune responses.