Children's Hospital Colorado

Respiratory Illness in Kids: How to Tell the Difference Between COVID-19, RSV, Flu and More

A young child sneezes into a tissue with their eyes shut while a caregiver holds a thermometer.

As a parent, you never want your kids to get sick. But it happens — and probably more often than you'd like — especially during the fall and winter. This is the time of year when illnesses like the common cold, influenza (flu), respiratory syncytial virus (RSV) and other viruses are widely circulating. Add in COVID-19, and you’re probably wondering what bug your kid picked up this time. 

Many respiratory illnesses in children have similar symptoms, which means it can be difficult to distinguish between the flu vs. COVID-19 vs. colds. But there are some subtle differences between these viruses. Children’s Hospital Colorado pediatric infectious disease specialist Samuel Dominguez, MD, PhD, offers guidance on common respiratory illnesses in kids, how to prevent them and what you should do if your child gets sick.

How to protect your family from respiratory viruses

The best way to prevent getting sick with COVID-19, RSV, flu or any other respiratory illness is to follow these healthy habits to stop germs from spreading

  • Stay home when you’re sick. 
  • Frequently wash your hands.
  • Cover your cough.
  • Stay up to date on your COVID-19 and flu vaccines, and get your infant or toddler the RSV monoclonal antibody shot if they’re eligible. 
  • Consider wearing a mask in indoor, crowded spaces when viruses are circulating at high levels in your community. 
  • If you’re sick, stay away from infants and young children until you feel better. If you have a child 6 months or younger — or one with underlying heart or lung conditions — remain cautious about close contact with others who have cold or flu symptoms.

Even with precautions, it’s likely that your family will catch a virus during cold and flu season, so it’s important to be prepared and recognize the differences between these common illnesses.

Symptoms quick chart

With the help of our experts, we created a chart for quickly comparing symptoms of COVID-19, the flu, RSV, common colds and allergies.

Note: This chart should only be used as a starting point. There are many different viruses that cause respiratory symptoms in children, and symptoms and treatments can vary from person-to-person. If your child is sick, talk with their pediatrician.

Signs and symptoms in kids COVID-19 Influenza (the flu) RSV/ bronchiolitis Common respiratory infections (colds) Seasonal allergies (hay fever)
Onset of symptoms Varies; typically gradual Sudden

Varies; typically starts mild

Varies Typically sudden or ongoing
New loss of taste or smell Sometimes Uncommon


Uncommon Sometimes
Fever Sometimes*; typically high fever Very common; typically high fever


Varies Never
Tiredness Severely tired Severely tired Common Varies Sometimes
Cough Very common; typically dry cough Very common; typically dry cough

Very common; often a wheezing cough  

Varies Sometimes
Headache Common Very common


Varies Uncommon
Loss of appetite/difficulty feeding for babies Sometimes Common


Varies Less common
Muscle and body aches Common Very common


Common Uncommon
Sore throat Common Common


Common Sometimes; typically mild
Runny nose/nasal congestion Common Common

Very common

Common Very common
Nausea or vomiting Sometimes Sometimes Sometimes Less common Uncommon
Chills Sometimes Very common Uncommon Less common Never
Diarrhea Sometimes Sometimes Sometimes Varies Never
Shortness of breath/breathlessness Sometimes Sometimes

Very common

Uncommon Uncommon
Wheezing or audible breathing Sometimes Sometimes

Very common

Sometimes Uncommon

*Less than half of children who are diagnosed with COVID-19 will have a fever. Even if your child does not have a fever, it is possible that they could have COVID-19.

Common respiratory illnesses in children

If your child is sniffling, coughing or has a fever or sore throat, it’s possible that they could have picked up a respiratory virus. For many healthy kids, these viruses cause a brief period of illness and discomfort before improving. But for very young children or those with compromised immune systems, even a common respiratory illness can be a cause for concern.

COVID-19 in kids

While COVID-19 infections are nowhere near their peak of the early days of the pandemic, the coronavirus is still circulating throughout Colorado and around the country. Widespread access to safe and effective COVID-19 vaccines has improved outcomes for those who catch the virus. But there are still some things that parents and caregivers should look out for as we move into cold and flu season.

What are COVID-19 symptoms in kids?

COVID-19 affects people differently. Coronavirus symptoms range from mild to severe, and not everyone will have every symptom. In general, symptoms in kids and teens may include:

  • Fever/chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches 
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Runny or stuffy nose
  • Nausea or vomiting
  • Diarrhea
  • Abdominal pain
  • Poor appetite (or poor feeding)
  • Rash

Why you should get the COVID-19 vaccine 

It’s true that most children who get infected with COVID-19 fare relatively well. They don’t end up in the hospital or experience lasting effects from the illness. It’s also true that the vaccines aren't 100 percent effective at preventing infection in kids or adults. This is because the virus keeps mutating, and the level of protection the vaccines offer changes as the virus mutates.  

However, Dr. Dominguez points out other important reasons to get vaccinated. “The data is very clear that the vaccine does prevent you from getting super sick with the virus,” says Dr. Dominguez. “And if you are around other kids who are high risk or are around grandparents, there are studies that show that you have a decreased risk of transmitting the virus, as well." 

Additionally, research shows that staying up to date on your COVID-19 vaccines can help prevent Long COVID, in which symptoms linger for months after the initial infection, although this is less common in kids.  

Read the updated COVID-19 vaccine guidelines from the CDC

Why COVID-19 testing is still important

Because COVID-19 is highly contagious and it can take longer for people to develop symptoms, a COVID-19 test can alert you as soon as possible if you have the virus — even if you were infected but don’t have symptoms.

“Knowing if you have the virus sooner means you can isolate and take other precautions sooner,” says Dr. Dominguez. “Taking a COVID test is one of the best things you can do to help control the spread of the virus.”

Tests for the flu and RSV are also available through your healthcare provider, as is a single test that detects the flu, COVID-19 and RSV all at once. Your pediatrician can recommend the type of tests your child needs based on their symptoms and risk factors, and those results can help guide your care plan. For example, we have treatments for COVID-19 that may be recommended for some patients, just like we have treatments that can help ease the symptoms or lower the risk of the flu.


Influenza (commonly known as the flu) is a highly contagious respiratory virus that is present year-round, but circulates widely in the fall and winter months, or cold and flu season. The flu causes cold-like symptoms that often come on suddenly and can range from mild to severe. Children under the age of 2, adults over age 65, pregnant and postpartum women, people taking certain medications and those with chronic medical conditions, including lung or heart conditions, can develop severe or life-threatening complications from the flu. 

Some of the primary symptoms of the flu overlap with symptoms of COVID-19, making it difficult to distinguish between the two illnesses. Fortunately, the accessibility of at-home COVID-19 tests can make it easy to determine if an individual is infected with COVID. If an individual is at high-risk for severe disease or would qualify for treatment, a flu test may also be recommended.

What are flu symptoms in kids?

Influenza symptoms include: 

  • Fever/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Tiredness
  • Nausea or vomiting
  • Diarrhea

Is the flu a concern this year?

Yes, the flu is always a concern, especially for those who are at a higher risk of severe disease from the virus, such as young infants, those who are immunocompromised or older adults. While it can be difficult to predict how severe the flu season will be, Dr. Dominguez says that there is evidence to suggest that the 2023-24 flu season will be “average.” This is welcome news after a cold and flu season that was longer and more severe than normal in 2022-23.

Should my family get the flu vaccine?

Yes, the best way to prevent the flu is for every adult and child over 6 months old to get the influenza vaccine as soon as cold and flu season begins, usually around the beginning of September. “Everyone should get a flu shot every year,” says Dr. Dominguez. “Not only does it reduce your chances of getting the flu, but if you do get it, your symptoms will likely be less severe.” The flu shot is also very effective in preventing severe disease, hospitalization and death, Dr. Dominguez adds.

Many health insurers, including Medicaid and Medicare, cover the full cost of the flu shot. But even if you don’t have insurance, you can find low-cost or no-cost flu vaccines. Ask your pediatrician or healthcare provider for more information or find a flu clinic in Colorado.

RSV in kids

Respiratory syncytial virus (RSV) is a common, cold-like infection that hits most kids before they turn 2. Though RSV typically circulates in the winter months, it’s made some unseasonal comebacks during the pandemic. In the fall and winter of 2022, children’s hospitals around the country saw a surge in RSV, straining emergency rooms and hospitals.

For healthy children, RSV can be similar to a cold. But infants or immunocompromised children are at risk of complications from the virus, such as bronchiolitis or pneumonia. According to the American Academy of Pediatrics, RSV is the most common cause of hospitalization for children under the age of one. While it is possible to get RSV multiple times, even within the same season, secondary infections are often less severe.

What are RSV symptoms in kids?

Call your pediatrician when you notice these symptoms of RSV:

  • High fever and ill appearance (though not all children with RSV experience fever)
  • Thick nasal discharge
  • Worsening cough
  • A cough with discolored mucus
  • Signs of dehydration
  • Signs they’re having trouble breathing: Look for short, rapid and shallow breaths or retractions, where the chest caves in and the belly expands with each breath
  • Unusual irritability or inactivity
  • Refusing to nurse or bottle feed

If your child is struggling to breathe, seek out emergency care.

What treatments or vaccines are available for RSV?

Most children recover quickly from RSV with at-home treatment, such as fever-reducing medication, nasal suction and plenty of fluids. In severe cases, RSV may require treatment in the hospital, so the child can receive oxygen and intravenous (IV) fluids.

Previously, there was only one monoclonal antibody shot available to prevent RSV in high-risk babies under 2 years old, palivizumab. The injection is given once a month during cold and flu season. But in the summer of 2023, the FDA approved nirsevimab, another monoclonal antibody injection that can be given to all babies and high-risk toddlers, as well as Abrysvo, a vaccine that can be administered during the third trimester of pregnancy to protect infants against RSV for up to six months. While these options are currently available in limited supplies, they represent a promising step in preventing severe RSV infections in babies and toddlers.

The common cold in kids

Common colds are normal. In fact, healthy children get about six colds a year. According to the National Institutes of Health, there are more than 200 different viruses, such as rhinoviruses, that can cause cold symptoms. 

What are cold symptoms in kids?  

Common cold symptoms include:

  • Runny or stuffy nose
  • Sneezing
  • Sore throat
  • Gray, yellow or green nasal discharge
  • Cough
  • Scratchy voice 

How can you tell the difference between a cold, the flu and COVID-19?  

It can be difficult to tell the difference between these respiratory illnesses. Generally, a cold is milder than the flu, and symptoms appear gradually. Flu symptoms are usually sudden and severe. With the flu, your child will likely have a high fever, a headache, severe tiredness, achy muscles and chills. For a common cold, they may have a low fever to start, but they won’t have a headache or muscle aches, and they won’t have chills. In very young children, fever may be the only symptom of flu infection. 

Because COVID-19 symptoms vary widely and often range from mild to severe, the only way to know for sure if your child has the virus is by taking a COVID-19 test.  

Ear, nose and throat infections

While ear, nose and throat conditions aren’t respiratory viruses, they’re often the result of illnesses like a cold or the flu. In the early stages of the pandemic, doctors were seeing fewer ear and sinus infections due to public health measures like social distancing and masking. In the fall of 2022, we saw an increase in bacterial and viral infections in kids, causing an uptick in ear, nose and throat conditions like ear infections, sinus infections and strep throat. In some cases, these conditions need to be treated by antibiotics.

“With the comeback of common respiratory illnesses and viruses like RSV, we’ve again seen an increase in strep throat and ear infections,” says Children’s Colorado pediatric otolaryngologist Sarah Gitomer, MD. “In fact, we’re seeing more complicated infections now than in the past several years.”

Enterovirus D68 and acute flaccid myelitis

Acute flaccid myelitis (AFM) is an uncommon but serious neurological condition.  One of the causes of AFM is a respiratory virus called enterovirus D68, abbreviated as EV-D68. AFM primarily causes limb weakness and paralysis, as well as loss of muscle tone, but other symptoms can also occur.

AFM first emerged in 2014, and experts at Children’s Colorado and the University of Colorado School of Medicine were the first to link an outbreak of AFM to the outbreak of the respiratory virus EV-D68. Prior to the pandemic this virus circulated every other year.  Colorado saw an increase in cases of EV-D68 in the fall of 2022 and experts predict that we will not see a large increase in cases again until late summer or early fall of 2024.  In rare cases, getting sick with this enterovirus can lead to AFM.

“Although AFM is rare, parents should know the symptoms and keep an eye out for them,” says Dr. Dominguez. “If your child is exhibiting signs of AFM, or any signs of paralysis, seek medical attention immediately.” 

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