RSV, COVID-19, or the Flu: How to Tell the Difference

Medically Reviewed By Darragh O'Carroll, MD

Respiratory syncytial virus (RSV), COVID-19, and influenza (flu) are similar viruses that spread differently and can cause severe symptoms. Medical attention is recommended to avoid complications.

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Many types of viruses cause disease in humans. Viruses can cause illnesses that affect just about any body system, including the digestive tract, skin, nervous system, and lungs.

Like most respiratory viruses, RSV, COVID-19, and the flu are present all year. However, they have seasonal increases in activity and illness. For all three viruses, the season starts around October, peaks around February, and drops off in the spring.

According to the Centers for Disease Control and Prevention (CDC), up to 41 million Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source  people in the United States become ill with the flu each year.

It’s hard to estimate how many people contract RSV, a cause of the common cold. However, it accounts for 2.1 million Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source  annual office visits in children younger than 5 years. With COVID-19, the CDC does not report annual illnesses, but it has likely affected about 150 million Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source  people in the United States.

Respiratory syncytial virus, COVID-19, and the flu spread differently

RSV, COVID-19, and the flu are respiratory viruses that spread differently. The primary way is through droplets expelled through coughs, sneezes, and talking. People nearby can inhale these droplets.

These viruses can be transmitted if droplets land on a hard surface that you touch and then touch your eyes, nose, or mouth.

COVID-19 requires airborne precautions. The particles that cause transmission can remain in the air for long periods and are 5 micrometers or smaller.

RSV and the flu need droplet precautions because air droplets are between 30 and 50 micrometers. Transmission is possible via coughing, sneezing, talking, or close contact with a person.

The CDC recommends wearing a face mask to prevent airborne and droplet transmission.

Direct contact, such as through kissing, may spread respiratory viruses, too.

Respiratory syncytial virus, COVID-19, and the flu cause similar symptoms 

As respiratory viruses, RSV, COVID-19, and the flu cause generally the same symptoms Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source , such as: 

Infants may display signs of feeling unwell, such as crying, irritability, or decreased appetite or activity level.

One tell-tale difference in symptoms is the loss of taste or smell that can happen with COVID-19. This symptom is unique to COVID-19 and usually does not occur with the flu or RSV.

Respiratory syncytial virus, COVID-19, and the flu can be serious for some people 

Of the three viruses, RSV is usually the mildest. It’s one of the viruses that causes the common cold Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source . For most people, it does become a severe infection. Though COVID-19 and the flu can be more intense than a cold, they are also usually not serious for most people. 

All three viruses cause illness that can become severe. In rare cases, symptoms may be life threatening for some people due to chronic conditions and pneumonia complications. COVID-19 can also cause problems with blood clots Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source .

RSV infections are common among infants and children. However, there is no medication formally approved for treatment. A 2022 study Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source  suggests RSV infections among children may increase after the pandemic.

Risk factors for severe illnesses from these respiratory viruses include a weakened immune system or a chronic condition, such as diabetes or heart or lung disease. This is true regardless of your age.

However, there are some differences in risk when it comes to age. For COVID-19, older age is the strongest Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source  risk factor for severe illness.

RSV and the flu can also become severe in older adults, especially those 65 years and older. These two viruses can also cause severe disease in young children and infants. COVID-19 is usually mild in this age group.

Respiratory syncytial virus, COVID-19, and the flu require a test to tell them apart

Because these three viruses have so many similarities, including their symptoms, testing is the only way Trusted Source Centers for Disease Control and Prevention (CDC) Governmental authority Go to source  to know which one is causing illness. A healthcare professional can test for each virus and let you know the results. 

The Food and Drug Administration (FDA) recently authorized an at-home Trusted Source Food and Drug Administration (FDA) Governmental authority Go to source  test for the flu and COVID-19. However, there currently is no option for testing at home for RSV. A doctor can help you get complete testing. They can also ensure you get the care you need, especially if you have a high risk for severe disease.

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Medical Reviewer: Darragh O'Carroll, MD
Last Review Date: 2023 Jun 5
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