In South Philadelphia, Karissa Justice, 28, also doesn’t have a car. Last month, when cough and flulike symptoms turned into severe shortness of breath, her doctor told her to call an ambulance. At Jefferson Hospital, she learned she hadn’t developed pneumonia, she said, so she was tested for the coronavirus and discharged. No one there seemed to know how she should get home without a car, she said, but they urged her to avoid close contact with people.