My brother-in-law tested positive for ‘rona. Fatigue, low grade fever and intestinal distress for 10 days. My sister lived with him, cared for him, drove his to the doctor and even slept in the same bed. She never got symptoms. If she was positive, she didn’t know it. She has been a teacher for 40 years. She must have had some immunity.
I know a guy whose 91-year old aunt died from corona in a Philadelphia area nursing home.
Her 94-year old husband shared the room with her. Despite sharing a room with a woman who died of this he never got sick, and never tested positive.