Vaccine resistance is the evolutionary adaptation of pathogens to infect and spread through vaccinated individuals, analogous to antimicrobial resistance.
We speak of vaccine resistance only if the immune evasion is a result of evolutionary adaptation of the pathogen (and not a feature of the pathogen that it had before any evolutionary adaptation to the vaccine) and the adaptation is driven by the selective pressure induced by the vaccine (this would not be the case of an immune evasion that is the result of genetic drift that would be present even without vaccinating the population).
[citation needed] Some of the causes advanced for less frequent emergence of resistance are[1][2] that For diseases that confer long lasting immunity after exposure, typically childhood diseases, it was argued that a vaccine may provide the same immune response as natural infection, so it is expected that there should be no vaccine resistance.
[3][4] If vaccine resistance emerges the vaccine may retain some level of protection against serious infection, possibly by modifying the immune response of the host away from immunopathology.
[5] The best known cases of vaccine resistance are for the following diseases Other less documented cases are for avian influenza,[24] avian reovirus,[25] Corynebacterium diphtheriae,[26] feline calicivirus,[27] H. influenzae,[28] infectious bursal disease virus,[29] Neisseria meningitidis,[30] Newcastle disease virus,[31] and porcine circovirus type 2.