A University of Iowa study estimates 381 missed opportunities to diagnose measles among 4,651 cases in Merative MarketScan Research Databases, as federal officials counted 4,852 U.S. cases in 2026 as of Oct. 29.
Researchers identified the cases in the databases from 2001 through 2023. They estimated that about 6.9% of patients had at least one missed opportunity. The 381 figure represents missed chances to recognize measles, not 381 separate patients with confirmed misdiagnoses.
Outpatient settings accounted for 81% of the diagnostic delays. The study associated respiratory antibiotic prescriptions and being younger than 2 with a greater likelihood of delay. Researchers said delays could contribute to transmission, particularly in outpatient care. The study also notes that U.S. measles elimination was declared in 2000.
The Centers for Disease Control and Prevention (CDC) reported 4,852 confirmed U.S. cases as of Oct. 29, compared with 2,289 cases in all of 2025. The Pennsylvania Department of Health counted 1,433 cases as of Nov. 2. EconoTimes previously covered the U.S. count passing 4,500 cases.
The Johns Hopkins Bloomberg School of Public Health said kindergarten MMR vaccination rates fell in most states between the 2024-25 and 2025-26 school years. Idaho had the largest drop, from 78.5% to 75.2%; Louisiana and Virginia each saw declines of about 2 percentage points.
