2. People Who Think They Are Immune May Not Be
Natural infection or two doses of MMR vaccine provides durable, generally life-long protection. Two doses of vaccine are 97%-98% effective; one dose is 90%-93% effective. In 1989, the American Academy of Pediatrics (AAP) and the Advisory Committee on Immunization Practices (ACIP) recommended a second dose of MMR vaccine, so most people born after 1988 received two doses of MMR and are immune.
Most, but not all, adults born before 1957 had measles and are immune. However, the situation may be more complex for people born between about 1957 and 1988. Most schools and many colleges, universities, and professional schools began to require a second dose of MMR for entry in the 1990s, so many people born in the late 1970s and 1980s have had two doses.
A less effective vaccine was used from 1962 to 1967. Some people who received this vaccine are still susceptible to measles. Those who were vaccinated between 1962 and 1989 received only a single dose and therefore may not be fully protected.
If possible, check vaccine records for administration of two doses of vaccine as evidence of immunity. Alternatively, measuring measles IgG titers can demonstrate immunity. Proof of immunity should be documented for all people working in the healthcare field. Given the current outbreak, proof of immunity is wise for people living in or traveling to areas with ongoing measles transmission.
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Cite this: Never Seen Measles? 5 Things to Know - Medscape - May 02, 2019.