Influenza (flu) and COVID-19 are contagious respiratory illnesses caused by different viruses. COVID is caused by infection with a coronavirus (SARS-CoV-2) first identified in 2019. The flu is an infection from the flu virus (influenza viruses).
COVID-19 is highly transmissible and spreads more quickly than the flu virus. When comparing the flu and COVID, COVID has higher mortality, often takes longer for symptoms to develop, and is contagious for longer.
Since the symptoms can be similar, specific testing is needed to tell what the illness is and to confirm a diagnosis. Board-certified emergency physician Dr. Barron Nason sees patients daily who seek to determine if their symptoms are the flu, COVID, allergies, or other. “Having a medical professional administer a test that detects both flu and COVID-19 allows you to get diagnosed and treated more quickly for the specific virus you have,” shares Dr. Nason. “Every patient has a unique set of circumstances that determine their ideal treatment plan. Factors such as history, secondary complications, age, and duration dictate treatment recommendations.”
Getting treated early for COVID and the flu can reduce your risk of getting very sick. COVID-19 and flu can have varying symptoms, ranging from no (asymptomatic) to severe.
- COVID-19 and flu share the following symptoms:
- Fever or feeling feverish/having chills
- Cough
- Shortness of breath or difficulty breathing
- Fatigue (tiredness)
- Sore throat
- Runny or stuffy nose
- Muscle pain or body aches
- Headache
- Vomiting
- Diarrhea
Differences between COVID and the Flu May Include the following:
- COVID takes longer from infection to symptoms than the flu.
- COVID can be contagious for longer than the flu.
- People can begin spreading the virus that causes COVID 2-3 days before symptoms start, but infectiousness is at its peak one day before symptoms begin.
- People can spread COVID without experiencing any symptoms.
- The virus that causes COVID is generally more contagious than flu viruses.
- COVID has more superspreading events than the flu.
- Secondary bacterial infections are more common with influenza than with COVID.
- Prescription influenza antiviral drugs are FDA-approved to treat the flu.
- Multiple FDA-licensed influenza vaccines protect against the four flu viruses.
- Multiple COVID-19 vaccines are approved in the United States to help prevent COVID-19.
