What to Know About Long COVID in Kids

5 minute read

There are lots of outstanding questions about Long COVID. How many people have it? Why do some develop it and not others? Do effective treatments exist?

When it comes to kids and Long COVID, there are even more questions and fewer answers. It wasn’t until earlier this year that experts even reached a consensus definition for pediatric Long COVID to use in research: one or more symptoms that last at least 12 weeks after a case of COVID-19, affect daily life, and can’t be explained by an alternate diagnosis.

“There are a whole host of things that we’re just trying to figure out,” says Dr. Kathryn Moffett, who is co-leading a study at West Virginia University School of Medicine that will track children over four years to better understand how many kids get Long COVID and why. “More research is done in adults, but we need answers in kids.”

Here’s what researchers know so far.

How common is Long COVID in kids?

Studies have arrived at different estimates for how many children develop Long COVID. But a June research review published in Scientific Reports, based on 21 previously published studies, concluded that about 25% of kids and adolescents who contract COVID-19 have symptoms that last at least four weeks—on par with the reported one in five U.S. adults who currently has Long COVID symptoms after an infection. However, the individual studies differed depending on how they were designed and defined Long COVID, whether kids had been vaccinated, and other factors.

A study published Aug. 12 in the journal Pediatrics reached a similar conclusion when looking at several hundred kids who were unvaccinated and sick enough to be hospitalized for either acute COVID-19 or MIS-C, an inflammatory condition associated with COVID-19. Roughly 25% had ongoing health issues two to four months later.

“The messaging has been, ‘Kids, if they get [COVID-19], will be fine,’” says study co-author Dr. Adrienne Randolph, a critical care specialist at Boston Children’s Hospital. “Yeah, most of them. But if your kid gets severe COVID-19, they’re at risk of having symptoms months later.”

Randolph’s study looked specifically at unvaccinated children sick enough to be hospitalized—a rare outcome for kids who get COVID-19—so it’s impossible to extend the findings to all kids. Plus, under the stress of the pandemic, symptoms like fatigue and headaches have become common across the board, and not all studies have been able to tease out how much of that is linked to Long COVID versus other factors, Randolph says.

For example, a Danish study published in the Lancet Child & Adolescent Health in June looked at infants through 14-year-olds who tested positive for COVID-19 but hadn’t necessarily been hospitalized, and compared them to similar-aged children who hadn’t tested positive. The kids who got COVID-19 were more likely to report lasting symptoms like rashes, difficulty concentrating, and mood swings—but not by much. Among kids ages 4 to 11, for example, 38% of those who’d had COVID-19 had symptoms lasting more than two months, compared to 34% of those who hadn’t had COVID-19. The study authors noted that “​​long COVID symptoms are the same as some ailments that are common in children,” which can make the disease difficult to study.

What are the symptoms of Long COVID in kids?

The Scientific Reports research review found that the three most common pediatric Long COVID symptoms were mood issues, fatigue, and sleep disorders. But reported symptoms ran the gamut, from inability to exercise and memory loss to nasal congestion and headaches.

An August report from the U.S. Centers for Disease Control and Prevention (CDC) looked at health records for a large group of children ages 0 to 17—more than 780,000 who’d had COVID-19, and more than 2.3 million who hadn’t—from March 2020 to January 2022. Kids with a previous COVID-19 infection were more likely to later report symptoms including smell and taste disturbances, circulatory issues, malaise and fatigue, and pain. By the end of the study period, kids who’d had COVID-19 were also more likely to have developed cardiovascular problems, kidney failure, and diabetes, but those conditions were rare in both groups.

What are the risk factors for Long COVID in kids?

Researchers are still trying to answer that question, but there are some clues. A Russian study published in the European Respiratory Journal found that children with allergic diseases—including asthma, eczema, and food allergies—and who were hospitalized for COVID-19 were at greater risk of lasting symptoms than hospitalized kids without these conditions. The Scientific Reports research review also listed older age, female gender, obesity, and preexisting conditions as potential risk factors. Kids who have severe disease seem more likely to develop Long COVID than those who have mild cases, according to the paper.

How can kids avoid Long COVID?

The only guaranteed way to avoid Long COVID is not to get infected in the first place. Getting vaccinated also reduces the risk of developing Long COVID after an infection, though it’s not clear to what extent. Still, Moffett says that should be a motivator for parents who are hesitant about vaccinating their children. As of Aug. 10, only about 30% of U.S. kids ages 5 to 11 were fully vaccinated, according to CDC data. The numbers are even lower for the youngest children; a Kaiser Family Foundation analysis of government data found that as of July 20, less than 3% of kids under age 5 had gotten at least one dose.

If a child does get infected, emerging evidence suggests they should rest as much as possible in hopes of preventing complications. Kids who already have Long COVID can also benefit from extra rest and reduced activity, as advocates from chronic disease groups #MEAction and Long COVID Families describe in a new guide.

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Write to Jamie Ducharme at jamie.ducharme@time.com