The flu and COVID-19 are both illnesses that have similar symptoms but are caused by different viruses. Both are preventable through vaccinations. Separate vaccines are used.
Health care providers strongly encourage people to be fully vaccinated against both illnesses to prevent getting sick. They worry that a surge in flu and COVID-19 cases could put a strain on hospitals.
“Flu and COVID-19 can both cause serious illness and hospitalization,” says Ghazala Sharieff, MD, MBA, Scripps Health chief medical officer, acute care operations and clinical excellence. “Fortunately, we have vaccines that are highly effective and widely available for protection.”
The following are frequently asked questions about the flu season, the COVID-19 pandemic and vaccine protection.
People can be infected by flu and COVID-19 at the same time. “Because symptoms of COVID-19 and flu are similar, it may be hard to tell the difference based on symptoms alone, and testing may be needed to help determine whether you have flu or COVID-19,” Dr. Sharieff says.
The CDC says it’s likely both viruses will be circulating this fall and winter. Relaxed COVID restrictions, such as social distancing, may result in an increase in flu activity.
Similarities in symptoms between flu and COVID-19 include:
- Fever or chills
- Shortness of breath
- Sore throat
- Runny or stuffy nose
- Muscle pain or body aches
- Vomiting and diarrhea in some cases
- Change in or loss of taste or smell, though this is more common with COVID-19.
Symptoms alone cannot tell you whether you have COVID or the flu. Testing is needed to confirm a diagnosis.
While both spread from person to person, SARS CoV-2, the virus that causes COVID-19, is more contagious than influenza viruses and can easily spread to a lot of people.
People tend to develop flu symptoms one to four days after infection. COVID-19 symptoms may appear two to 14 days after infection.
Both illnesses can result in complications, including:
- Respiratory failure
- Fluid in lungs
- Heart attack
- Multiple organ failure
- Worsening of chronic condition
- Secondary infections
Most people who get the flu will get better on their own in a few days to two weeks. Some will experience severe complications.
COVID complications can include blood clots and post-COVID conditions that can last weeks or months.
Those at highest risk of severe illness from both flu and COVID include:
- Older adults
- People with certain chronic health conditions, such as asthma, heart disease and diabetes
- Pregnant people
The flu vaccine is recommended for everyone 6 months or older, with few exceptions. Ideally everyone should be vaccinated by the end of October. Vaccinating later also works since the flu peaks in February and may even continue into May.
It is safe to receive both vaccines at the same time if you are eligible and the timing coincides. The Centers for Disease Control and Prevention provides guidelines for COVID vaccines, including boosters.
Scripps patients can use the MyScripps portal to schedule vaccination for flu, COVID-19, pneumonia and other illnesses.