The protection from measles due to a past infection / vaccination lasts for a lifetime. Therefore, any of the following scenarios can be taken as proof that an individual has immunity against measles:

(a) documented proof of completion of a course of vaccination involving two doses of measles (or measles-containing) vaccine given at least four weeks apart;

(b) serological evidence of immunity against measles; or

(c) laboratory confirmation of past measles infection.