One-year-old River Jacobs is held by his mother, Caitlin Fuller, while he receives an MMR vaccine from Raynard Covarrubio, at a vaccine clinic held by the Lubbock Public Health Department on March 1 in Lubbock, Texas. A measles outbreak in West Texas has led to more than 500 cases, 57 hospitalizations and the deaths of two school-age children. Jan Sonnenmair/Getty Images hide caption

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