The number of measles cases in the U.S. has surpassed the record-breaking tally for all of 2025, with five more months of 2026 still to come. Measles cases spikeIn November, international health officials will meet to determine if the U.S. and Mexico have lost their measles-free status. Story continues below advertisementMeasles cases are undercountedWhile measles cases in the U.S. are climbing, it may be impossible to say exactly how far-reaching the spread is. There, the 997 total is likely an undercount, the state health department has said, but it doesn’t know by how much. Shetty expects to keep seeing measles cases and even outbreaks because so many people are unprotected.