There are scenarios in which going to a hospital is necessary. If a patient is short of breath or can't keep fluids down because of nausea, these are signs of a problem that needs immediate attention, Zich said. Excessive vomiting or sweating from fever can lead to dehydration, which is serious and requires treatment.
Very young children, senior citizens and people with underlying health conditions should also see their doctor, the CDC's Frieden said. They are the populations most susceptible to serious illness. "Rapid treatment in the first 48 hours can make a big difference," he said.