COVID's Long Haulers – Thousands of Americans infected with the Coronavirus, who seemingly recovered, are still experiencing worrisome symptoms, some very debilitating. Anderson Cooper reports on these patients whose conditions doctors still don't fully understand. Where Did They Go? – Enrollment data from the largest school districts in the U.S. compiled by 60 MINUTES this fall found unprecedented numbers of students unaccounted for when school started – the first school year to begin in the pandemic. Sharyn Alfonsi reports. 90+ – 60 MINUTES returns to a Southern California retirement community where it first reported on a landmark study of people over the age of 90. Lesley Stahl finds half of the people she interviewed six years ago still alive and providing valuable information on the secrets to a long and healthy life.