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What is the difference between COVID-19 and Influenza (Flu)?COVID-19 and Influenza (Flu) are both contagious respiratory illnesses caused by different viruses. COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2) and flu is caused by infection with influenza viruses. Because the symptoms of flu and COVID-19 are similar, it may be hard to tell the difference between them based on symptoms alone. Testing may be needed to help confirm a diagnosis.
Both COVID-19 and flu symptoms can range from no symptoms (asymptomatic) to severe symptoms.
| Symptoms | FLU | COVID-19 |
| Fever or feeling feverish/chills | frequent | frequent |
| Cough | frequent | frequent |
| Shortness of breath or difficulty breathing | not often | frequent |
| Fatigue (tiredness) | frequent | frequent |
| Sore throat | frequent | not often
|
| Runny or stuffy nose | sometimes | not often |
| Muscle pain or body aches | frequent | frequent |
| Headache | sometimes | sometimes |
| Vomiting and diarrhea | rare* | sometimes |
| Loss of taste or smell | not described | sometimes |
*More common in children than adults
How long do symptoms take to appear after exposure and infection?
For both COVID-19 and flu, several days can pass between a person becoming infected and when that individual begins to experience illness symptoms. If a person has COVID-19, it could take longer to develop symptoms than with the flu.
- A person with flu may develop symptoms between 1-4 days after exposure to the virus.
- A person with COVID-19 may develop symptoms between 2-14 days after exposure to the virus, but usually is between 4 and 7 days.
How long can someone spread the virus?
For both COVID-19 and flu, it is possible to spread the virus before experiencing any symptoms. If a person has COVID-19, they may be contagious for a longer period of time before symptoms than if they had flu.
- Most people with flu are contagious for about 1 day before showing symptoms.
- Older children and adults with flu appear to be most contagious during the initial 3-4 days of their illness and symptoms, but many remain contagious for about 7 days.
- Infants and people with weakened immune systems can be contagious for longer periods of time.
- People with COVID-19 can spread the virus for about 2 days before experiencing signs or symptoms and remain contagious for at least 10 days after signs or symptoms first appeared.
- If someone is asymptomatic or their symptoms go away, it is possible to remain contagious for at least 10 days after testing positive for COVID-19.
How does the virus spread?
Both COVID-19 and flu can spread from person-to-person, between people who are in close contact with one another (within about 6 feet). Both are spread mainly by droplets when people with the virus (COVID-19 or flu) cough, sneeze, or talk. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. It may be possible that a person can get infected by physical human contact (e.g. shaking hands) or by touching a surface or object that has the virus on it and then touching his or her own mouth, nose, or possibly eyes. Both flu virus and the virus that causes COVID-19 may be spread to others by people before they begin showing symptoms, by people with very mild symptoms or by people who never developed symptoms (asymptomatic).
Who is at high-risk for severe illness?
Both COVID-19 and flu can result in severe illness and complications. Those who may be at highest risk include:
- Older adults
- People with certain underlying medical conditions
- Pregnant women
The risk of complications for healthy children is higher for flu compared to COVID-19. However, infants and children with underlying medical conditions are at increased risk for complications due to both flu and COVID-19. School-aged children infected with COVID-19 are also at higher risk of Multisystem Inflammatory Syndrome in Children (MIS-C), a rare but severe complication of COVID-19. Additional complications associated with COVID-19 can include:
- respiratory failure
- blood clots in the veins and arteries of the lungs, heart, legs or brain
- kidney failure and heart abnormalities
Most people who get flu will recover in a few days to less than two weeks, but complications can include:
- pneumonia
- heart complications.
How can Flu and COVID-19 be treated?
People who are hospitalized with flu or at high-risk of flu complications are treated with antiviral drugs as soon as possible. Remdesivir is an antiviral agent that appears to help people with COVID-19 and is currently used to treat COVID-19. Studies are in progress to learn more. Both illnesses are primarily treated with supportive care.
Is there a vaccine to prevent Flu or COVID-19?
There are multiple influenza vaccines produced annually to protect against the 3 or 4 flu viruses that scientists anticipate might circulate each year. The best way to protect yourself and your loved ones against influenza (flu) is to get a flu vaccine every flu season. The flu vaccine does NOT prevent COVID-19. Currently, there is no vaccine to prevent COVID-19. Vaccine developers, researchers, and manufacturers are expediting the development of a vaccine to prevent COVID-19.
Is it possible to have the Flu and COVID-19 at the same time?
It is possible to test positive for flu (as well as other respiratory illness) and the virus that causes COVID-19 at the same time.
Differences between COVID-19 and Flu
| | COVID-19 | Flu |
How many days after exposure will I get sick from the virus? | 2-14 days, but usually between 4 and 7 days | 1-4 days |
How long can someone spread the virus?
| 2 days before symptoms start to 10 days after symptoms started | 1 day before symptoms start to 7 days after symptoms started |
How does the virus spread? | Mainly by respiratory droplets | Mainly by respiratory droplets |
Who is at high risk for complications? | | Older adults People with certain underlying medical conditions Pregnant women Children younger than 5, especially those under the age of 2
|
How can person infected be treated? | Primarily treated with supportive care. Remdesivir is an antiviral agent that is currently used. | Primarily treated with supportive care. Antiviral drugs should be used as soon as possible. |
Is there a vaccine against the virus? | No. Research and development for a vaccine is underway. | Yes. There are multiple vaccines produced annually. |
