Everybody. We must all make preventing spread of infection a top priority. That means frequent and thorough hand washing (or use of hand sanitizer), covering our coughs and staying home if we’re sick. Seek medical attention if you have Covid-19 symptoms (dry cough, fever, difficulty breathing) for more than two days. And don’t wear a face mask unless you have cough or fever. Outside of health care settings, a mask’s main benefit is to help keep someone who is sick from infecting others. We aren’t going to have enough masks, and we need to prioritize those that we have for health care workers, those caring for ill people and people who have symptoms.

People who are medically vulnerable. Medical vulnerability is not about chronological age but about how healthy people are. A healthy and vigorous 79-year-old is almost certainly at lower risk than a 55-year-old with diabetes and lung disease. People who are medically vulnerable will stay safer if they avoid large-group meetings, crowded enclosed spaces (including airplanes) and they may want to telework and stay 6 feet away from others as much as possible, as well as limit the number of people they come into contact with.

Health care providers. Hospitals and other health care facilities need to prepare to surge safely. Strict infection control procedures must be implemented in all areas of every facility, including proper triage of every patient and isolation of all suspected cases. As in a busy flu year, hospitals should be ready for a surge of people with mild symptoms and the “worried well” — people concerned that every cough might mean they have Covid-19. If there is lots of severe illness, it may become necessary to postpone elective surgery, train nurses to provide respiratory therapy and expand the number of patients who can be supported with intensive care.