Seniors can start making appointments for the vaccine at the United Center starting this Thursday. Starting at 8:30 a.m. After seniors have signed up anyone eligible for a vaccine as part of the Phase 1B+ group can begin to make appointments at 4 p.m. on March To register and get an appointment, visitwww.zocdoc.com/vaccineor call (312) 746-4835 from 8 a.m. to 8 p.m. Monday through Saturday and 8 a.m. to 4 p.m. on Sunday.The United Center will also be open for a number of appointments on March 9 before they have the full opening on March 10.