It's worse than you think. Measles is one of the most contagious viruses known: among unvaccinated people, 90 percent of those exposed will be infected. Oh, and among older people, it can cause a fatal nervous system disease and wipe out immunity to other infections https://arstechnica.com/health/2025/02/unvaccinated-school-aged-child-dies-of-measles-in-texas-amid-growing-outbreak/