Similarities and Differences between Influenza and COVID-19

What is the difference between influenza and COVID-19?

Influenza and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. The cause of COVID-19 is coronavirus (SARS-CoV-2) infection, which was first discovered in 2019. Influenza is caused by infection with the influenza virus.

From what we know, COVID-19 spreads more easily than the flu. Efforts to maximize the proportion of Americans vaccinated against COVID-19 remain critical to reducing the risk of severe COVID-19 disease and death. We have more information about COVID-19 vaccines and how they work.

For some people, COVID-19 can cause more severe illness than the flu. People infected with COVID-19 may take longer to develop symptoms and may remain contagious longer than those infected with the flu.

It’s impossible to tell the difference between the flu and COVID-19 just by looking at symptoms, as some signs and symptoms of the two illnesses are the same. Specific screening tests are needed to know what the disease is and confirm the diagnosis. If a medical professional provides you with a specific test that detects both the flu and COVID-19, you will be able to diagnose your infection more quickly and receive treatment. Getting COVID-19 and flu treated as soon as possible can reduce your risk of serious illness. Screening tests can also let you know if a person has both the flu and COVID-19, although this is uncommon. People who have both the flu and COVID-19 may become more seriously ill than people who have only the flu or only COVID-19. Additionally, some people with COVID-19 may have post-COVID-19 illness (also called persistent COVID-19 illness).

We are learning new things about COVID-19 and its virus every day. This page compares COVID-19 to influenza based on the best information available to date.