In previously vaccinated and unvaccinated patients in California, vaccine failure measles cases were less ill than cases that occurred in unvaccinated individuals; however, these cases still required the same amount of public health effort in tracing contacts as in cases of those who were unvaccinated. All confirmed measles cases reported to the California Department of Public Health from January 2000 through December 2015 were reviewed. Researchers compared clinical characteristics (rates of hospitalization, cough, coryza, conjunctivitis, and fever) between the previously unvaccinated, those who had 1 dose of vaccine, and those who had ≥2 doses of the measles vaccine. They found:

• There were 232 confirmed measles cases in which vaccination status was verified.
• Of these, 80% were unvaccinated, 9% had 1 dose of measles vaccine, and 11% had ≥2 doses of measles vaccine.
• Those who had ≥2 doses of measles vaccine had lower rates of hospitalization, cough, coryza, conjunctivitis, and fever compared to those who had 1 dose of the measles vaccine or who were unvaccinated.