The wails pierced the walls of the walk-in clinic tucked among rundown homes in the heart of Venezuela’s capital. Artemis Parra got one vaccine in each arm, for polio and measles. The shots were free at the government site, and they filled gaps in the 1-year-old’s vaccination record. But they weren’t enough to meet national requirements for children her age. Artemis needs two more, at a cost of $400—a bill her unemployed mother and government-worker father can’t afford.