A healthy living blog from Marshfield Clinic Health System

COVID-19 and influenza: You can help prevent the spread of both

This year, we are heading into an influenza (flu) season in the midst of the COVID-19 pandemic. COVID-19 and influenza are both contagious respiratory illnesses caused by different viruses that can lead to missed school and work, hospitalization, and sometimes, death.

Because some of the symptoms of influenza and COVID-19 are similar, it may be difficult to tell the difference. Your health care provider will help by testing to confirm a diagnosis.

A woman recovers from the flu.

You can help prevent the spread of COVID-19 and influenza.

In this post, Marshfield Clinic Health System experts share their advice to help protect you and others from COVID-19 and influenza.

Symptoms cannot identify the virus

COVID-19 and influenza can cause a variety of symptoms. You can have mild cold symptoms to severe, life-threatening pneumonia. And, unfortunately with COVID-19 and influenza (more common with COVID-19), you may not experience any symptoms, but can still spread the infection to others.

Common symptoms of COVID-19 and influenza include:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue (tiredness)
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache

“If you experience any of these symptoms, you should contact your doctor to be tested,” said Dr. Edward Belongia, an infectious disease epidemiologist at Marshfield Clinic Research Institute. “Many people with COVID-19 have no symptoms, but they can still spread the virus to others. This is why facemask use and social distancing are so important. Many people are spreading COVID-19 in the community without symptoms. If they spread it to someone at high risk, that person might end up in the intensive care unit.”

Loss of taste or smell is one symptom of COVID-19 that does not typically occur with influenza. It is important to contact your health care provider if you develop these symptoms or have had contact with a person who has COVID-19.

Spreading COVID-19 and influenza

The time interval from exposure to illness (incubation period) is about four to five days on average for COVID-19, and slightly shorter for influenza. The risk of spreading COVID-19 is greatest one to two days before symptoms develop and during the first few days of illness. A person with COVID-19 should remain isolated until at least 10 days have passed since illness began and symptoms have resolved for at least 24 hours. For influenza, Belongia said, “CDC recommends staying home for at least 24 hours after fever has resolved.”

Both COVID-19 and influenza can spread from person-to-person in close contact (within about six feet) and through the air, especially from people who are sneezing, coughing or talking.

“COVID-19 is contagious for the entire population,” Belongia said. “No one should think they are immune or protected. People who have recovered from COVID-19 are likely to have some protection against reinfection, but no one knows how long the protection will last.”

The risk of getting COVID-19 is greatest when groups of people are together indoors with poor ventilation. You should try to avoid indoor group gatherings to protect yourself and your family.

Wearing a mask can help when it is impossible to avoid other people in public locations like grocery stores, or at church or school. However, it is very important to maintain at least six feet distance from others whenever possible. Wearing a mask helps prevent you from spreading infection, but does not offer much protection for you in a crowd of people. Wearing a facemask and maintaining physical distance are both important to reduce the risk of COVID-19.

COVID-19 and influenza spread mainly by droplets in the air, but you can still become infected by direct physical contact. This includes shaking hands, or touching a contaminated surface or object. When that happens, you can become infected if you touch your eyes, nose or mouth. Frequent handwashing or use of hand sanitizer can help reduce your risk.

Call your provider to be tested

Testing for COVID-19 and influenza uses nasal swabs – maybe even one swab for both viruses – but the tests are different.

Health System providers will determine if you need testing and which tests should be ordered based on your symptoms and if you had close contact with someone who has COVID-19.

If you have flu-like symptoms or know you have been exposed to someone with COVID-19, you should contact your provider right away. In addition, the Health System has a 24-hour Nurse Line available at 844-342-6276 that can provide screening information and schedule testing if needed, or you can use the online screening to determine your next steps.

It can take one to two days to receive COVID-19 results from the lab, and less time than that for influenza results. While you wait for results, you need to continue to protect yourself and others by using safety precautions – stay home, wash your hands and clean high-touched areas. Click here for a handout on steps to take while you wait for COVID-19 results.


Centers for Disease Control and Prevention (CDC)

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