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

If your child is feeling sick, it’s best to call their primary care provider for recommendations. (If you don’t have a pediatrician, you can call our ParentSmart Healthline.) They can help assess your child’s symptoms and determine if COVID-19 testing — or a test for other viruses — is an appropriate next step.

At-home COVID-19 tests are widely available at most pharmacies and are generally considered accurate for detecting the presence of the coronavirus. These tests provide results in about 10 minutes, which means you can take precautions sooner and prevent others from getting sick, too.

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, consider retesting in 1 to 2 days, or requesting a PCR test, which is more sensitive, from your primary care doctor.
• You were exposed to someone who has COVID-19 but do not have symptoms. In this case, test 5 days after exposure. Positive results indicate that you have the virus and should take the recommended precautions. If the test is negative, test again in 1 to 2 days.
• You are attending an event or large gathering during times when viruses are circulating at high levels in your community, especially when people at the event are at risk of severe complications from COVID-19. Consider testing immediately prior to the event and skip it if you get a positive result.

The Centers for Disease Control and Prevention (CDC) recommends that people who test positive for COVID-19 stay home and isolate for at least five days, when you are the most infectious. If an individual must be around others during this time, wear a high-quality mask, like an N-95. When isolation can end depends on the severity of your symptoms. Here is an overview of guidance from the CDC:

• If you or your child are symptom-free, you can end isolation after day 5.;
• If you had symptoms, but they are improving, you can end isolation after day 5, if you are fever-free for 24 hours without the use of fever-reducing medication.
• If you or your child is moderately or severely ill or has a weakened immune system, continue to isolate through at least day 10 and consult a healthcare provider.

COVID-19 vs. the flu: Which is more serious?

While most kids experience mild symptoms of both COVID-19 and the flu, in some cases, these conditions can become very serious. When we compare the numbers year by year in people younger than 18, it’s clear that COVID-19 has caused more cases, hospitalizations and deaths than the flu does in a typical year in the United States.

For the past 15-plus years, flu-related deaths in children reported to CDC during regular flu seasons have ranged from 37 to 199 deaths each year. From the start of the pandemic until summer 2023, more than 1,800 children under the age of 18 have died from COVID-19. That averages out to around 600 deaths per year.

Death isn’t the only risk associated with COVID-19. Some people who’ve been infected with the virus experience Long COVID, in which symptoms linger for months after the initial infection, although this is less common in kids. Children can also experience other unique concerns from COVID infections, such as myocarditis, multisystem inflammatory syndrome (MIS-C), abnormal liver enzymes, fatigue, hair loss and skin rashes.

Most children who are infected by COVID-19 are asymptomatic, meaning they don’t have any symptoms, or they have mild symptoms. In rare cases, though, there are two reasons some children get very sick. 

“One is just a really bad COVID-19 infection that occurs during what we call an acute — or sudden — infection,” says Dr. Dominguez. “The other is a condition called multisystem inflammatory syndrome in children, or MIS-C, which usually occurs 2 to 6 weeks after the infection.” 

Most experts think that MIS-C is caused by the body’s immune response to a COVID-19 infection. In 2022 and 2023, experts have seen fewer cases of MIS-C compared to the first two years of the pandemic. However, parents should still be aware of the symptoms. The best way to prevent MIS-C is to take recommended precautions against COVID-19. 

Children’s Colorado is involved in several national research studies to learn more about MIS-C. A team of our multidisciplinary specialists developed comprehensive guidelines to effectively diagnose and treat children with MIS-C, including nearly 200 who’ve been treated at Children’s Colorado. The guidelines are now nationally recognized and shared with hospitals across the country.

What are MIS-C symptoms in kids?

MIS-C symptoms can include:

• Fever
• Severe abdominal pain
• Vomiting
• Diarrhea
• Rash
• Red eyes or red lips
• Trouble breathing
• Seeming confused/sleepy
• Persistent pain or pressure in the chest
• Pale, gray or blue-colored skin, lips or nail beds, depending on skin tone

If your child is showing these symptoms after a COVID-19 infection, call your primary care provider. In a life-threatening emergency, you should always call 911.

Most kids get RSV before they turn 2, and most recover quickly. But RSV can cause serious complications for infants, preemies, and babies and young children with underlying medical conditions. RSV can lead to pneumonia and bronchiolitis, when the small airways in the lungs become inflamed and clogged with mucus. Even kids without underlying conditions can get very sick with RSV. Kids and babies with more severe cases of RSV often require a trip to the emergency department or care in the hospital so they can receive breathing support, like oxygen.

RSV can cause re-hospitalization for babies who have been in the Neonatal Intensive Care Unit (NICU) due to prematurity or other medical conditions. Some NICU babies that require oxygen are eligible for an antibody that treats RSV, which the care team would recommend along with other vaccines for babies with medical conditions.

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 the recently approved RSV vaccine 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. 

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.”

About 85% of children experience at least one ear infection during childhood. Some ear infections can resolve without antibiotics. But Dr. Gitomer says parents should call their child’s primary care provider if they see a combination of the following symptoms:

• Ear pain
• Drainage of fluid from the ear
• Tugging or pulling at an ear
• Fussiness or crying more than usual
• Trouble hearing sounds
• Loss of balance
• Headache

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

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.

Sinus infection symptoms include:  

• Fever (generally only associated with acute sinusitis)
• Yellow or green nasal discharge
• Cough
• Headache
• Facial pain or facial pressure
• Nasal congestion (snoring and mouth breathing)
• Postnasal drip (the feeling of mucus building up in the throat or dripping from the back of your nose)

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 symptoms last more than 10 days. If your child’s sinus symptoms have not improved in this time period, it’s time to call a doctor.

“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 Dr. Gitomer. “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.”

In these cases, Gitomer says it’s important to contact your primary care provider. Your child will likely need antibiotics and may need to be seen by a pediatric otolaryngologist,: an ear, nose and throat surgeon.

“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.” 

Strep throat symptoms in kids can include:

• A sore throat that comes on rapidly
• Painful swallowing
• Fever
• Headache
• Swollen tonsils
• Red spots on the roof of the mouth or tonsils
• Swollen lymph nodes in the neck
• White streaks of pus on the tonsils

If your child is experiencing these symptoms, call their pediatrician 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. 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.”

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 AFM, which tends to occur about one week after their respiratory infection.

Primary symptoms of AFM include sudden onset of:

• Arm or leg weakness
• Loss of muscle tone and reflexes
• Additional symptoms of AFM may include:
• Difficulty moving the eyes or drooping eyelids
• Facial droop or weakness
• Difficulty with swallowing or slurred speech
• Pain in arms or legs
• Pain in neck or back

In extremely rare cases, additional complications and injury to the nervous system may occur. If your child is showing signs of this rare condition, seek medical care immediately.