A new analysis of medical records has revealed a sharp increase in U.S. adults over age 50 seeking measles immunity tests, known as titer tests, as the nation faces rising measles outbreaks. According to data from the healthcare analytics firm Truveta, the rate of these tests among older adults spiked significantly during 2025 and early 2026, coinciding with major outbreaks in Texas and South Carolina.
The study, which examined electronic health records from nearly 30 million patients, found that in 2025, titer testing occurred at nearly seven times the rate observed in previous years. Researchers suggest that high-profile outbreaks are driving public health-seeking behavior, with many older adults uncertain of their vaccination status because they lack paper records from their youth.
While the Centers for Disease Control and Prevention (CDC) recommends that adults born during or after 1957 without proof of immunity get the MMR vaccine, many patients are opting for blood tests to confirm their status first. However, medical experts, including Dr. Margot Savoy of the American Academy of Family Physicians, note that receiving an MMR booster is often more efficient and cost-effective than testing, as the vaccine is generally covered by insurance and poses no harm to those who may already be immune.
As the U.S. continues to see measles circulate in diverse public settings, experts emphasize that for those unable to locate immunization records, the simplest and most accessible path to protection remains a booster dose of the MMR vaccine.