Young children really are the germiest

By Katia Hetter, CNN

(CNN) — Kids are really the germiest members of the household.

In case you didn’t know that from experience, new research published in the journal Pediatrics confirmed that respiratory viruses circulate frequently in school settings, and younger children are more likely to carry these viruses and become ill.

But why are younger children more likely to catch and spread infections? What does this mean for schools and households as we head into peak respiratory virus season, with relatives of all ages hugging and spreading those germs around? There must be something we can do now to help prevent illness.

To help answer these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at George Washington University. She previously was Baltimore’s health commissioner. She also has two kids in elementary school, so she’s dealt with her share of germs outside of work.

CNN: What did the study find about how we spread viruses?

Dr. Leana Wen: This study is one of the most detailed analyses of how respiratory viruses circulate in schools. Researchers followed more than 800 students and staff members from a large public school district in Kansas City, Missouri, from November 2022 through May 2023. Participants were asked to collect weekly nasal swabs and to complete short surveys about any symptoms of respiratory illness, such as cough, sore throat, congestion or fever. The goal was to track both the presence of viruses and the frequency of symptomatic illness over time.

The results showed that respiratory viruses and the illnesses they cause were very common. More than 85% of all participants had at least one virus detected during the study, and over 80% experienced at least one episode of acute respiratory illness. That means their symptoms were significant enough to interfere with normal activities, keeping them home, rather than just dealing with a mild runny nose or a brief cough.

Younger children in prekindergarten and elementary school had the highest rates of both infection and illness on average. By contrast, older students and staff tested positive and fell ill less often.

Many children tested positive even when they felt well, which suggests that schools may serve as a steady reservoir of respiratory viruses, with young students acting as carriers in school to infect one another and taking those viruses home to their household members.

CNN: What kinds of viruses were most common in the study?

Wen: Rhinoviruses, which cause the common cold, were detected most often and were found in 65% of participants at some point during the school year. Coronaviruses that often cause seasonal colds were found in about 30%. The virus that causes Covid-19, SARS-CoV-2, was found in about 15%. This led researchers to emphasize that even when Covid-19 or flu receive more attention, these “everyday” respiratory viruses remain widespread.

We also learned infections occurred even outside of the timelines of major outbreaks, meaning that virus circulation in schools can be steady throughout the season, not just during surges of flu and Covid-19.

CNN: Why are younger children more likely to catch and spread viruses?

Wen: Young children’s immune systems are still developing, and many haven’t yet encountered the wide range of respiratory viruses that circulate each fall and winter. That means their immune defenses are less experienced, making them more likely to get sick when exposed.

Children also have habits that make it easier for viruses to spread: They touch their faces often, they share toys and supplies, and they may not cover coughs or wash hands as consistently as older kids and adults. In classrooms and child care settings, they are in close quarters with other children for hours at a time. And because some viruses can spread even when a child has only mild symptoms or none, they can pass infections to others without realizing it.

CNN: What do these findings mean for families?

Wen: Kids may have as many as eight colds a year, and it may often feel as if the family is just getting over one round of illness when the next one strikes.

For most healthy children, respiratory virus infections are mild, but illness can still cause considerable disruption, like missed school days, missed work for parents and strained family routines. Recognizing that pattern can help parents anticipate and take practical steps early, such as helping kids improve hygiene habits and planning for backup child care before illness strikes.

CNN: What can parents do to reduce the risk of infection?

Wen: The most effective approach is simple but consistent prevention. The US Centers for Disease Control and Prevention recommends frequent handwashing with soap and water for at least 20 seconds, especially before meals and after coughing, sneezing or using the bathroom.

Be aware that viruses can linger on commonly touched surfaces, so it is also a good idea to wash your hands after touching doorknobs, shared utensils and toys. If soap and water aren’t available, an alcohol-based hand sanitizer is the next best option, though these are not effective against all viruses.

Children should be taught to cover coughs and sneezes with their elbow or a tissue, and to avoid touching their eyes, nose or mouth. Families should also clean and disinfect commonly touched items and surfaces such as toys, doorknobs, light switches and countertops daily, particularly when someone in the household is sick.

Avoiding close contact, such as kissing or sharing drinks, with anyone who has respiratory symptoms also can limit spread. And staying home from school or work when sick remains one of the most effective ways to stop viruses from moving through communities.

CNN: Do ventilation and masks help?

Wen: Yes. Opening windows when weather allows; using portable air purifiers with high-efficiency particulate air, or HEPA, filters; and running HVAC systems with high-quality filters can help reduce the concentration of airborne viruses indoors. These steps are especially useful in classrooms and homes where multiple family members are sick at once.

Wearing a well-fitting, high-quality mask in crowded indoor spaces also can reduce the risk of contracting respiratory infections or spreading your illness to others. Such masks should be considered for people with significant underlying medical conditions or during local spikes in illness.

CNN: Are there vaccines that help reduce some of these illnesses?

Wen: Yes — and staying up to date is important. The flu vaccine, recommended annually for everyone 6 months and older, is a very important tool to prevent serious illness. Covid-19 vaccines continue to protect against hospitalization and severe disease. Vaccines against respiratory syncytial virus, or RSV, are also available for older adults, pregnant women and certain infants.

While there’s no vaccine for the many common cold viruses, getting recommended vaccines can reduce the likelihood of severe disease for these illnesses and also makes it less likely that multiple infections will overlap at once.

It’s important to remember that vaccines don’t always prevent you from getting sick from a certain virus, but even if you get sick, they can significantly lessen the likelihood of severe illness and even death.

CNN: What’s your takeaway as we head into another winter virus season?

Wen: The sheer number of respiratory infections kids get during the winter can feel relentless for families, but most cases are mild and part of the natural process of building immunity. Prevention measures matter. They can’t eliminate all illness, but they can reduce how often it occurs and far it spreads. The goal isn’t to prevent every sniffle but to keep families healthier and kids well and able to learn throughout the long winter ahead.

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