Learn more about the symptoms, causes and prevention of this potentially deadly viral infection that attacks the respiratory system., The signs and symptoms of both diseases can range from no symptoms to mild or severe symptoms. Because COVID-19 and the flu have similar symptoms, it can be hard to diagnose which condition you have based on your symptoms alone., Flu is a general term for seasonal influenza, which is a viral infection that attacks your respiratory system. Symptoms often come on suddenly and may seem like a cold at first, with a runny nose or congestion, sneezing and sore throat., COVID-19 symptoms usually start 2 to 14 days after exposure to SARS-CoV-2. Flu symptoms usually appear about 1 to 4 days after exposure to an influenza virus. COVID-19 can cause more-serious illnesses in some people than can the flu. Also, COVID-19 can cause different complications from those of the flu., Symptoms of COVID-19 and the flu appear at different times and have some differences. With COVID-19, you may experience loss of taste or smell. COVID-19 symptoms generally appear two to 14 days after exposure. Flu symptoms usually appear about one to four days after exposure., Get answers to your flu vaccine questions, including whether the vaccines are effective, what forms are available and what side effects to expect..