People walk through the nearly empty tourist area of Quincy Market, Wednesday, March 11, 2020, in Boston. Public health officials in Massachusetts said Wednesday that they are monitoring more than 445 people under self-quarantine for possible symptoms of the coronavirus, which has affected global tourism and business. For most people, the virus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia. The vast majority of people recover from the new virus. (AP Photo/Steven Senne)