COVID-19 and the Flu

What You Need to Know

Getting sick this flu season comes with added worry. The COVID-19 pandemic is still spreading and will be circulating at the same time as this year’s flu. If you get sick in the coming months, how will you know if it’s the flu, COVID-19 or a less serious virus like a cold?

COVID-19 and influenza are both respiratory illnesses with similar symptoms, but they’re caused by different viruses. COVID-19 is caused by a new strain of coronavirus (SARS CoV-2) and the flu is caused by influenza viruses. Both are spread mainly by droplets expelled when people with the virus cough, sneeze or talk.

While we're still learning about COVID-19, we do know it’s extremely contagious. Some infections are mild, but it can cause major health problems, leading to hospitalization and death. Because it’s a new virus that our bodies have not seen before, we have no immunity and the lasting effects are still unknown.

The flu is also a dangerous illness and can lead to serious complications — especially in seniors, babies, pregnant women and people with compromised immune systems. Every year, millions of people in the U.S. get sick with the flu and more than 200,000 end up in the hospital, according to the Centers for Disease Control and Prevention (CDC).

The good news is you can get vaccines for both COVID-19 and the flu. However, you should avoid getting any other vaccines two weeks before and after getting vaccinated for COVID-19.

Similar Symptoms

If you get sick, it could be tricky to know if you have the flu or COVID-19. They have similar symptoms: Fever, chills, congestion, cough, muscle aches, nausea, headache and fatigue. Although there is symptom overlap, there are two key hallmarks of COVID-19 infection:

1. New loss of taste or smell, without nasal congestion.
2. Shortness of breath.

Other signs to look out for: the severity of symptoms can be much worse with COVID-19 and critical illness can develop quickly. Another difference is time between exposure and when a person typically gets sick. With COVID-19, a person usually develops symptoms about five days after infection, but the range is two to 14 days after exposure. With the flu, you typically get sick one to four days after exposure. Also, how it makes you sick differs. When you get the flu, it often makes you feel very sick within a few hours after symptoms start. COVID-19 may not make you feel very sick until a few days after it starts.

In general, colds are much milder than either the flu or COVID-19. Cold symptoms tend to come on gradually over a few days and can include stuffy nose, sneezing, coughing and a scratchy throat. In most cases, a cold won’t cause a fever or extreme fatigue and doesn’t lead to serious health problems.

It’s important to remember that with every illness not everyone gets all the symptoms. Review our chart detailing the symptoms of these respiratory illnesses. You can also check the CDC website for a complete list of COVID-19, flu and cold symptoms.

Stay Healthy: Get a Flu Shot, Wear a Mask and Social Distance

Getting a flu shot this year is more important than ever. It can offer protection against this year’s flu strains and help keep you out of the hospital. The CDC recommends everyone age 6 months and older be vaccinated against the flu every year.

“It’s vitally important to get your flu shot this season, with COVID-19 circulating at the same time,” says Jeffrey Silvers, M.D., medical director of infection control at Sutter Health. “The flu shot can help keep you out of the hospital.”

Flu season starts in fall and lasts until March or April. It takes about two weeks after vaccination to be fully protected, so you should get a flu shot before flu begins spreading — ideally by the end of October. You can still get vaccinated later, even into winter.

To learn more about flu and getting your flu shot, view our Flu Resources and watch this Flu Vaccine video, featuring Dr. Silvers.