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

2/7/2025 15 min. read

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 prevent respiratory illnesses

The Centers for Disease Control and Prevention (CDC) updated its respiratory virus guidance in 2024. The CDC now recommends focusing on five core prevention strategies and adding extra precautions as needed.  

The core prevention strategies include:

  • Staying up to date on your COVID-19 and flu vaccines and getting your infant or toddler the RSV monoclonal antibody shot if they’re eligible.
  • Frequently washing your hands and practicing good hygiene, such as covering your coughs and sneezes, and regularly cleaning high-touch areas.  
  • Bringing clean air into your home by opening windows and using air purifiers, as well as moving group gatherings outside whenever possible.  
  • Treating the flu or COVID-19 if you or your child test positive and have risk factors for severe illness.  
  • Staying home and away from others when you’re sick.  

Additional prevention measures are encouraged during times when respiratory illnesses are circulating in your area, especially for those who are considered high-risk. Consider taking extra precautions if you were recently exposed to a respiratory virus or are feeling sick. These prevention measures include wearing a mask, avoiding crowded areas and testing if you’re not feeling well or planning to be around high-risk individuals.    

When to return to normal activities after a respiratory illness 

No one likes to be sick. Not only does it feel uncomfortable, but it’s also disruptive to work and school schedules. But when you or your child is feeling under the weather, it’s important to stay home so that you can recover — and stop germs from spreading

The CDC recommends that you or your child can return to normal activities when your symptoms are improving and you no longer have a fever without using fever-reducing medications for at least 24 hours. Consider taking extra precautions for the next five days, as you could still be contagious.

Even with prevention, 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 doctor or healthcare provider.

Signs and symptoms in kids COVID-19 Influenza (the flu) RSV 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

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

Common

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

Uncommon

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

Common

Varies Less common
Muscle and body aches Common Very common

Uncommon

Common Uncommon
Sore throat Common Common

Sometimes

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 serious. 

COVID-19 in kids

While COVID-19 infections are nowhere near their peak of the early days of the pandemic and fortunately the newer strains tend to cause less severe illness, 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 parents should still be aware of coronavirus symptoms, which can range from mild to severe. Remember that COVID-19 affects people differently, and not everyone will have every symptom.  

Why you should get the COVID-19 vaccine 

It’s true that most children who get infected with COVID-19 fare relatively well. They usually don’t end up in the hospital or experience lasting effects. It’s also true that the vaccines aren't 100% effective at preventing infection. 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.  

When should you test for COVID-19?

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 can be very helpful in controlling the spread of the virus.”

At-home COVID-19 antigen tests are widely available and generally considered accurate. These tests provide results in about 10 minutes, which means you can take precautions sooner and prevent others from getting sick. 

You should use an at-home COVID-19 test if: 

  • The person being tested is at least 2 years old. Currently, there are no home tests approved for kids under 2.
  • You have COVID-19 symptoms. A positive test shows that you have the virus and should take the recommended precautions. If the test is negative and you still have symptoms, consider retesting in 1 to 2 days. 
  • You were exposed to someone who has COVID-19 but don’t have symptoms. In this case, test 5 days after exposure. Positive results indicate that you have the virus and should take precautions. If the test is negative, test again in 1 to 2 days.  

Tests for the flu and RSV are also available, as is a single test that detects the flu, COVID-19 and RSV. Testing for RSV alone is less common. Your doctor or healthcare provider can recommend the type of tests your child needs based on their symptoms and risk factors. (If you don’t have a pediatrician, you can call our ParentSmart Healthline.) Knowing whether your child has COVID-19, the flu, RSV or another virus can help your doctor provide appropriate care.  

What is MIS-C?

Rarely, a child who was infected with COVID-19 can develop a condition called multisystem inflammatory syndrome in children, or MIS-C, which usually occurs 2 to 6 weeks after the infection. MIS-C is a condition in which different body parts can become inflamed, including the heart, lungs, kidneys, brain, skin, eyes or digestive organs. Most experts think that MIS-C is caused by the body’s immune response to a COVID-19 infection.  

Cases of MIS-C peaked in 2021 and 2022 but have since dropped dramatically. “We're not sure if it’s because of widespread immunity to COVID-19 or if the new variants aren’t as likely to cause MIS-C,” says Dr. Dominguez.  

However, parents should still be aware of the symptoms, which include fever, severe abdominal pain, trouble breathing, chest pain and confusion. Some patients with MIS-C can also present with a rash and red eyes. If your child is showing these symptoms, call your doctor. In a life-threatening emergency, call 911.  

The best way to prevent MIS-C is to take recommended precautions against COVID-19. “We do know that the vaccines reduce the risk of developing MIS-C, as well,” Dr. Dominguez says.  

Influenza

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.

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 doctor 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 in recent years. In the fall and winter of 2022, children’s hospitals around the country saw a surge in RSV, straining emergency rooms and hospitals.

While most kids recover quickly from RSV, it can cause serious complications for infants, preemies, and babies and young children with underlying medical conditions. Even kids without underlying conditions can get very sick with RSV.

Seek medical care if your child is showing symptoms of severe RSV, including a worsening cough, difficulty breathing or eating, wheezing or showing signs of extreme fatigue or dehydration. In some cases, RSV can also lead to pneumonia and bronchiolitis, when the small airways in the lungs become inflamed and clogged with mucus. If your child is struggling to breathe, call 911 or go to the emergency room.

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.  

To prevent severe RSV, the CDC recommends that infants younger than 8 months old receive the monoclonal antibody shot, Beyfortus (nirsevimab), in the fall before respiratory season begins, or within the first week of a baby’s life if they’re born between October and March. Beyfortus might also be recommended for toddlers under 18 months old who are at increased risk for severe illness due to RSV.

Another option is a maternal RSV vaccine, which is administered during the third trimester of pregnancy to protect infants against RSV for up to 6 months. Your doctor can recommend the best option for you and your baby.  

Can adults and older children get RSV?

Yes, adults and older children can and do get RSV, but they typically don’t get as sick as young children or seniors. Dr. Dominguez puts it this way: If you or a child in your home has a cold, consider that it might be RSV, and act accordingly. Wash your hands, cover your cough, stay home when you’re sick — and don’t kiss any babies or grandparents until you feel better. 

Dr. Dominguez also recommends that adults over the age of 60 receive one of the approved RSV vaccines as an added layer of protection against the virus.  

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

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 like ear infections, sinus infections and strep throat aren’t respiratory viruses, they’re often the result of illnesses like a cold or the flu. In some cases, these conditions need to be treated by antibiotics

Ear infections 

About 85% of children experience at least one ear infection during childhood. Some ear infections can resolve without antibiotics. Symptoms of ear infections include ear pain, tugging or pulling at the ear and drainage or fluid. 

When kids have multiple ear infections in a matter of months, it may be time to meet with an ear, nose and throat specialist to discuss ENT surgery

Sinus infections 

The sinuses are the system of nasal cavities in the skull. These cavities are usually empty, but they can become blocked with fluid and germs when you have a viral infection like a common cold. The blockage causes the tissue along these cavities to become inflamed, and that’s when a sinus infection (or sinusitis) can occur. 

A sinus infection typically resolves on its own with over-the-counter medications and does not require parents to seek medical care for their child. Occasionally, you can get a bacterial infection in your sinuses. The most common sign is when your sinusitis symptoms last more than 10 days. In these cases, call a doctor, as your child may need antibiotics.  

“It’s important to treat these longer infections with antibiotics because, in rare cases, untreated sinus infections can spread to areas around the sinuses,” says pediatric otolaryngologist Sarah Gitomer, MD. “When this happens, symptoms can include a red, puffy or bulging eye, decreased or painful movement of the eye or vision loss, or severe headaches.” 

Strep throat 

“A sore throat is a common symptom of the flu and a cold, so there’s always a question of how to tell when it’s something more,” says Dr. Gitomer. “A sore throat with a cough, runny nose or raspy voice indicates that your child likely has a viral infection, not a bacterial infection like strep throat.”

If your child is experiencing symptoms of strep throat, including a sore throat that appears quickly, fever or spots on the roof of the mouth or tonsils, call your doctor and tell them you suspect your child may have strep throat so they can be tested. 

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. This virus usually circulates every other year between August and October. 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.”

An EV-D68 infection can look a lot like the common cold, but some patients also have asthma-like symptoms, including shortness of breath and wheezing. Some cases can require hospitalization, especially for kids with asthma. If your child has been sick, keep an eye out for symptoms of AFM, which tends to occur about one week after their respiratory infection.  

What to keep in mind during cold and flu season 

It’s natural to want to know which respiratory virus made you or your child sick. In some cases, such as if you or a family member is at risk for severe disease, it can be beneficial to seek testing and treatment. But keep in mind that the symptoms of respiratory viruses are similar, testing isn’t always accurate, and most of the time, your child can recover at home without a trip to the doctor's office. 

The most important thing you can do when your child is sick is to keep them home so they don't get others sick. With rest, hydration and fever-reducing medicine, your child will be back to themselves in no time.