COVID-19 can spread through a family like wildfire, frequently infecting other people in a household within days of someone carrying the coronavirus home with them, new research shows. More than half of people in households with COVID-19 patients wound up contracting the virus themselves, usually within five days of the first patient developing symptoms, according to findings from the U.S. CDC. The study tracked 101 people initially diagnosed with COVID-19 in the cities of Nashville, Tenn., and Marshfield, Wis., between April and September, according to a report published Oct. 30 in the CDC's Morbidity and Mortality Weekly Report.