Melanie Leffler, a mother of two in Sydney, Australia, had four COVID-19 vaccines. But on Nov. 19, 2022, after coming down with a sore throat and a runny nose, Leffler tested positive for COVID. She said goodnight to her family—her husband, Mick Hogan, and their two daughters, Clemmie (age four) and Lottie (9 months). They would never speak to her again.