Decades after the introduction of the MMR vaccine, measles was declared eradicated in the United States in 2000, with the two-dose MMR series recommended for lifelong immunity. Medical expert Dr. Nicole Saphier stated that for most individuals, the two doses offer around 97% effectiveness against measles. Deciding whether to receive an additional measles vaccine depends on factors such as vaccination history, age, and health condition. Adults who received both doses as children are likely protected unless they fall into a high-risk category, in which case a booster may be considered. People born before 1957 may have natural immunity due to likely exposure before vaccines were available. Those vaccinated between 1963 and 1968 should verify the type of vaccine they received, as an earlier version was found to be less effective and was eventually withdrawn. While antibody levels may decrease over time, cases of measles in fully vaccinated individuals are rare. Routine third doses are not currently recommended but can be considered after checking antibody levels through a blood test. Dr. Marc Siegel also stressed the importance of measles vaccinations, especially with the increase in measles cases globally. It is advised for travelers to areas experiencing measles outbreaks to consult a doctor for a “titer test” to determine immunity status and consider a booster if necessary. The live virus MMR vaccine is not suitable for pregnant women or those with compromised immune systems. As of 2025, the CDC has reported 164 measles cases in the U.S. this year, with the majority occurring in Texas.
According to doctors, measles vaccines administered in the past may have reduced efficacy in certain states including California, Georgia, Kentucky, New Jersey, and Rhode Island. The original information can be found in an article titled “Measles vaccines given long ago could be less effective now,”.
