COVID-19, Flu & RSV: How Are These Respiratory Illnesses Different?

Multiple viruses that can cause respiratory illness are circulating and causing infections at higher levels than expected at this time of year. This increase in respiratory disease activity has led to increased emergency department visits and more children needing hospital stays than usual.

With multiple viruses circulating this flu season, it is important to know the difference between the common cold and something more serious.

Flu, COVID-19, RSV or a cold?

Respiratory illness can be caused by several common viruses, including influenza, COVID-19 and respiratory syncytial virus (RSV). These illnesses may appear similar and often share similar symptoms.

  • COVID-19 is caused by the SARS-CoV-2 virus. Symptoms include fever, cough, fatigue, congestion, shortness of breath, sore throat, headache, sneezing, vomiting, diarrhea or loss of taste/smell. COVID-19 symptoms can appear 2-14 days after infection.
  • Influenza, sometimes called the flu, is often caused by two main types of influenza viruses, influenza A and influenza B. Symptoms include fever, cough, fatigue, stuffy nose, shortness of breath, sore throat and headaches. Symptoms show up about 1-4 days after being exposed to the virus.
  • RSV is caused by a virus known as respiratory syncytial virus. Symptoms include a fever, cough, fatigue, stuffy nose, shortness of breath, sneezing, fast/short breaths, flaring nostrils, wheezing and grunting, poor eating or loss of appetite, and head bobbing or chest caving in between and under ribs with each breath. Symptoms of RSV are typically the most severe on days 3 through 5 of illness and can last up to 7 days. RSV is common in late fall through early spring and most commonly affects children. Most children will get RSV by their second birthday.
  • The common cold can refer to a respiratory illness caused by many different viruses, most commonly rhinovirus, adenovirus, human coronavirus, human parainfluenza virus and human metapneumovirus. Symptoms can include fever, cough, fatigue, stuffy nose, sore throat and sneezing.

What is the best way to tell these illnesses apart?

As each of these respiratory pathogens can cause similar illnesses with similar symptoms, testing is important to determine the true cause of illness. Individuals should consult with their health care provider to discuss testing and proper treatment, if needed. Testing may also be offered at local public health units or pharmacies. Click here for additional information regarding at-home testing for diseases such as COVID-19.

Why is it important?

Each of these viruses has the potential to cause severe illness, leading to severe outcomes such as hospitalization or death. The Centers for Disease Control and Prevention (CDC) estimates that, so far in the 2023-2024 season, there have been at least 7 million illnesses, 73,000 hospitalizations and 4,500 deaths from flu alone.

Certain groups are more at risk for developing complications due to infections with these viruses. Adults 65 years of age or older, those with chronic health conditions, American Indian/Alaskan Natives and pregnant individuals are at increased risk of developing serious complications from the flu. Infants and young children, as well as older adults and those with chronic medical conditions, may also be more likely to develop severe illness due to RSV infection.

What is the best way to protect yourself?

Staying up to date on vaccines remains one of the best ways to effectively protect yourself from serious illness due to the flu, COVID-19 or other vaccine-preventable diseases. The protection from vaccines can help to prevent serious illness or hospitalization in people at risk of serious problems from fluCOVID-19 (and its complications, like MIS-C) and other viruses.

Everyone 6 months and older should get the influenza vaccine each year. While getting vaccinated by the end of October can provide the best protection against influenza, flu season can last until the end of May. For more information on COVID-19 vaccinations, visit our immunization page.

This season, several new immunizations became available to prevent the spread of RSV. Two RSV vaccines have been licensed by FDA and are recommended by CDC for adults ages 60 and older, using shared clinical decision-making. A maternal vaccine has also been licensed and recommended during weeks 32 through 36 of pregnancy to protect infants. Finally, an RSV preventative antibody has been licensed and recommended for infants and some young children.

Currently, there is no vaccine to protect against RSV or the common cold. For RSV, some infants who are at increased risk of severe outcomes (born significantly premature, had a heart defect or have a weakened immune system) can receive a medication called palivizumab.

There are additional tools to help stop viruses from spreading. Stay home and away from others if you are sick. Proper hand-washing practices can cut down on the spread of illness; individuals should be encouraged to wash their hands with soap and water or use an alcohol-based sanitizer. Children should learn to cover their mouth and nose with a tissue when they cough or sneeze (and then put the tissue in the trash). Wearing a mask in public can help prevent COVID, flu and other viruses from spreading.


If your child is sick and you have any questions or concerns about their symptoms, don’t hesitate to call your health care provider. It is important for all children to stay up to date on immunizations, sports physical examinations and routine care.

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