When 24-year-old Andrea Giraldo arrived in New York City from Miami to ring in 2018 with friends in the East Village, she had no idea how gravely ill she would soon become.

Her ordeal began with terrible leg pain, which sent Ms. Giraldo to a New York City hospital that is not affiliated with the Mount Sinai Health System. There, she was treated for blood clots in her leg vein and sent home. But later that night in her friend’s apartment, she had trouble breathing and collapsed.

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