“This year seems to be a banner year for norovirus occurring — there’s a lot of cases being reported,” said Dr. Michael Sweat, the director of the Center for Global Health at the Medical University of South Carolina. The virus is typically most prevalent from November to April, he added.

— The flu, caused by influenza viruses that are always changing, leads to fever, chills, cough, sore throat, runny nose, body aches, headaches and feeling tired. Flu symptoms tend to hit more quickly than cold symptoms, and can last anywhere from a few days to two weeks.