Feeling sick? Wondering if it’s COVID-19 or the flu? This seems to be a common question, especially during respiratory season. While there are several differences between the two viruses, they share many of the same symptoms, which can be quite confusing.
It’s important to know that COVID-19 and influenza are both respiratory illnesses but completely different viruses. Here’s a breakdown.
Similarities
You cannot tell the difference between the two viruses from symptoms alone. Both COVID-19 and flu have many of the same symptoms, including:
- Fever
- Cough
- Shortness of breath or difficulty breathing
- Fatigue
- Sore throat
- Runny or stuffy nose
- Muscle pain or body aches
- Headache
- Vomiting
- Diarrhea
There are other similarities between the two viruses:
- Vaccines help prevent severe illness, hospitalization, and death. They also help prevent the spread of the viruses to others.
- A person may never experience symptoms with either virus.
- Both viruses spread from person to person between those who are in close contact.
- Older adults, people with underlying medical conditions, and people who are pregnant are at increased risk of experiencing complications.
- Both viruses can cause serious health complications.
- Face masks can help prevent further spread.
Differences
COVID-19
- Caused by infection with a coronavirus (SARS-CoV-2).
- Spreads more easily than flu.
- Can cause more severe illness, even in healthy people.
- People may take longer to show symptoms.
- A person may be contagious for a longer period of time.
- A person typically experiences symptoms from two to five days and up to 14 days after infection.
- The virus can be spread two to three days before symptoms begin but peaks one day before symptoms begin.
- People are considered contagious for about eight days after symptoms begin.
- Loss of taste and smell has been found to be an early symptom of infection.
- Those infected with COVID-19 can develop post-COVID-19 conditions or multisystem inflammatory syndrome (MIS-C).
Flu
- Caused by infection with a flu virus (influenza virus).
- A person typically experiences symptoms from one to four days after infection.
- People can be contagious for about one day before developing symptoms.
- Older children and adults are generally most contagious the first three to four days of illness. Babies and people with weakened immune systems can be contagious for longer.
- Most people will recover on their own in a few days to two weeks.
- Diarrhea is a more common symptom among kids than adults.
How to tell the difference
The best way to determine if you have COVID-19 or the flu is by getting tested. COVID-19 testing is now widely available in the U.S. There are two types of tests—PCR and antigen. If you’re not sure what test to use, the CDC can help you determine which one to take.
A negative COVID-19 test means the test did not detect the virus, but this doesn’t rule out that you could have an infection. If you have been exposed and test negative with an antigen test, test again 48 hours after the first negative test if you have symptoms. Test a total of three times each 48 hours apart if you have been exposed, test negative, and do not have symptoms.