Measles is returning to countries that had eliminated it. An estimated 95,000 people died of measles in 2024, most of them young children, and 57 countries reported large or disruptive outbreaks in 2025, while only 77% of children worldwide received the second dose of measles-containing vaccine, far below the 95% needed to stop transmission. This Outbreak Report reviews the global situation in 2026, explains why reassuring national averages can hide clusters of unvaccinated people where outbreaks take hold, and sets out the measures that interrupt transmission: two-dose coverage in every district, targeted catch-up vaccination, sensitive surveillance, rapid response with post-exposure prophylaxis, infection control in health-care settings and better access for the communities that health systems have never reached.