Top 6 most contagious illnesses parents need to know about

Children are often exposed to a variety of contagious germs, especially in group settings like schools, daycare centers or playgrounds. As a parent, understanding the most contagious illnesses and how to recognize them can help you take proactive steps to protect your little ones.

From the common cold to more serious children’s viruses, let’s break down why viruses are contagious and discuss the most contagious illnesses that we pediatricians tend to see during the school year.

Are viruses contagious?

Viruses are highly contagious. They can quickly spread from person to person in a few different ways, including respiratory droplets, direct contact or touching surfaces contaminated with the virus.

For example, illnesses like the flu, common cold (upper respiratory infection) and RSV are easily transmitted when an infected person coughs, sneezes or shares items with others.

Now, think about how children operate when they’re together. All those kids touching and playing as kids do, putting their hands all over surfaces in classrooms and playgrounds, sharing toys and snacks.

Plus, kids aren’t the best at washing their hands and covering their coughs. This makes schools and daycares hotbeds for a lot of contagious viruses.

Most contagious illnesses

Let’s talk about a few viruses in particular that we see most heavily during the school year, especially the fall and winter months. If you think your child is showing symptoms of any of these most contagious illnesses, talk to your pediatrician.

1. Respiratory syncytial virus (RSV)

RSV is one of the many viruses that can cause respiratory illness―illnesses of the nose, throat and lungs. This virus typically occurs in the late fall through early spring months but can start earlier some years.

RSV shows up like a common cold with these symptoms:

• Runny nose
• Fever  
• Cough
• Short periods without breathing (apnea)
• Trouble eating, drinking or swallowing
• Wheezing
• Flaring of the nostrils or straining of the chest or stomach while breathing
• Breathing faster than usual or trouble breathing
• Turning blue around the lips and fingertips 

These symptoms typically last a week or two. However, RSV can cause difficulty breathing and lead to serious illness, especially for babies and older adults. It’s important to monitor your child’s symptoms and know when to seek care if you’re concerned about your baby with RSV.

There are options available to help protect babies against RSV. If a mother receives the RSV vaccine during pregnancy, it provides her baby with protection against RSV for the first six months of life after birth. Infants under 8 months old can also be given the RSV monoclonal antibody, which has shown to be highly effective at preventing serious illness.

2. Influenza (flu)

We’re all familiar with this one—the dreaded flu. The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat and sometimes the lungs.

Flu symptoms usually come on suddenly and can include:

• Fever or feeling feverish/chills
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue (tiredness)
• Vomiting and diarrhea (more common in children)

Fortunately, the flu vaccine is highly effective. Remember to get your whole family vaccinated against the flu every fall.

3. Rhinovirus and adenovirus (common cold)

Adenoviruses and rhinoviruses are viruses that cause the common cold, also referred to as an upper respiratory infection. While symptoms are usually mild, these viruses can lead to upper respiratory infections. These colds are most common during the fall and spring.

4. Parainfluenza (croup)

Parainfluenza viruses commonly cause respiratory illnesses in young babies and children. Symptoms typically include fever, runny nose and cough, but these viruses can lead to more severe illness such as croup or pneumonia.

5. Coxacki (Hand, foot and mouth disease)

This virus causes hand foot and mouth disease and is traditionally seen the most during school season. Hand, foot and mouth disease is especially common in children under 5 years old.

Although very contagious, the illness is usually not serious and most children have mild symptoms for 5 to 10 days. Symptoms of hand, foot and mouth disease usually include:

• Fever
• Mouth sores
• Skin rash commonly found on the hands, mouth and/or feet

6. COVID-19 (coronavirus)

COVID-19 can cause a wide range of symptoms, including:

• Fever
• Cough
• Trouble breathing
• Symptoms of a cold such as a sore throat, congestion or a runny nose
• Chills
• Muscle pain
• Headache
• Loss of taste or smell
• Nausea or vomiting
• Diarrhea
• Tiredness

COVID-19 illness is usually mild in children but can lead to serious complications like MIS-C.

Protecting against children’s viruses

The good news is, you can help protect against these children’s viruses. We all learned a lot in the COVID-19 pandemic and taught our kids how to do a lot of the goods things—washing hands, distancing when you can, covering your sneezes and coughs with the inside of your arm. Continue encouraging (and modeling) these healthy habits.

And when it comes to the flu and COVID-19, the easiest way to protect your children is by getting them vaccinated.

If you think your child might be showing symptoms of one of these illnesses, talk to your child’s doctor for guidance.

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