Last July, when her immediate family tested positive for Covid-19, Breanna Aguilar did not fit into any groups considered at higher risk for severe disease.

She is 31 years old, a pet sitter and former fitness teacher who once ran a half marathon. She was, by most measures, healthy.

When Aguilar got Covid-19 she lost her sense of taste, had mild fevers and muscle weakness. She could barely keep anything down yet gained about 30 pounds. Later, she developed pelvic pain, cystic acne, breast tenderness, headaches, brain fog and extreme fatigue.