An adolescent girl, devoid of a detectable humoral immunity to measles virus despite two inoculations of live, attenuated vaccine, developed an exaggerated atypical rubeola illness following exposure to wild virus. This observation suggests that attenuated virus may be capable of immunologically sensitizing some individuals as has been described with killed virus vaccine.

The vaccine failed to produce antibodies in this girl, and as a result, increased sensitization to the natural (wild) measles - producing exaggerated symptoms.