Flu or COVID-19?
What Do I Have?
Understanding the similarities and differences between influenza and COVID-19 can help you make informed decisions about your health.
Patient Resource · November 2, 2024
Overview
Influenza (flu) and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by infection with a coronavirus (SARS-CoV-2) first identified in 2019.
Similarities
Both flu and COVID-19 share many common features:
- — Both can cause fever, cough, shortness of breath, fatigue, sore throat, runny nose, and body aches
- — Both spread mainly through respiratory droplets from person to person
- — Both can range from mild to severe illness, and in some cases can be fatal
- — Both can lead to pneumonia, respiratory failure, and other serious complications
- — Both can affect people of all ages, though older adults and those with underlying conditions face higher risk
Key Differences
Cause
Flu is caused by influenza A and B viruses. COVID-19 is caused by SARS-CoV-2, a novel coronavirus.
Loss of Taste or Smell
Loss of taste or smell is more commonly associated with COVID-19 than with flu.
Incubation Period
Flu symptoms typically appear 1–4 days after exposure. COVID-19 symptoms may appear 2–14 days after exposure.
Spread
COVID-19 appears to spread more easily than flu and can cause more serious illness in some people.
Testing
Because symptoms overlap, testing is the only way to confirm which illness you have. Speak with your doctor if you are unsure.
What You Should Do
- — Stay home and rest if you feel unwell
- — Contact your doctor or clinic if symptoms worsen or you are in a high-risk group
- — Get tested to confirm your diagnosis
- — Stay up to date on flu and COVID-19 vaccinations
- — Seek emergency care if you experience difficulty breathing, persistent chest pain, confusion, or bluish lips
Learn More
For the full CDC comparison of flu and COVID-19 symptoms, transmission, and treatment:
cdc.gov/flu/about/flu-vs-covid19.html →Patient Resource Library
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