Measles cases in U.S. by March 31? is a active prediction market event on Polymarket with 7 markets, $150.4K total volume, and $33.3K in liquidity. Key markets: Will there be at least 1600 measles cases in the U.S. by March 31, 2026?; Will there be at least 1400 measles cases in the U.S. by March 31, 2026?; Will there be at least 1450 measles cases in the U.S. by March 31, 2026?.