Sorting Out Long COVID Symptoms in Babies

By the time many children with lingering symptoms of COVID-19 reach Lael Yonker’s pediatric pulmonology clinic, they have likely been told those problems are “just a cold.”

“When kids come to me, they’re very frustrated. They often will cry just because I’m listening to them and I’m not questioning whether or not they have long COVID,” Yonker, MD, associate professor of pediatrics at Massachusetts General Hospital in Boston, said. “I’m trying to address their symptoms.”

Often, family members bring up the possibility of long COVID, she said. That’s because when caregivers relay the symptoms of poor appetite and sleepiness, most pediatricians do not think the chronic condition could be a possible diagnosis, she said.

Until now, only small studies had been published on characterizations of the condition in infants, toddlers, and preschoolers, Yonker said.

But new research published in JAMA Pediatrics found distinct patterns of long COVID symptoms in young children.

Researchers from the NIH-funded RECOVER-Pediatrics Consortium analyzed data from over 1000 children aged 0-5 years, comparing those with a history of SARS-CoV-2 infection to uninfected peers.

The study found that 14% of infected infants and toddlers and 15% of infected preschoolers had probable long COVID, similar to rates in teens and school-aged children.

For infants and toddlers, the most strongly associated and prolonged symptoms associated with a history of COVID-19 infection were poor appetite, trouble sleeping, wet and dry cough, and stuffy nose. In preschool-aged children, daytime tiredness, and dry cough were prominent. Teens and school-aged children are more likely to have memory trouble, lightheadedness, and other neurologic issues.

The findings may challenge the assumptions of clinicians that very young children are less affected by long COVID, held in part because this population often cannot describe what they are experiencing.

“There is an underappreciation among parents and pediatricians that long COVID can present in younger children,” said Suchitra Rao, MD, an associate professor of pediatrics at the University of Colorado in Aurora, who was not involved in the study. “Much of the existing literature has focused on adults, so this is an important study which can shed more light on how younger children present with lingering symptoms.”

Symptoms Often Last Months in Young Kids

Rachel Gross, MD, an associate professor of pediatrics at the NYU Grossman School of Medicine and Bellevue Hospital Center in New York City and lead author of the new study, said identifying long COVID in very young children can be challenging.

“They have limited verbal communication, limited social skills, and even a limited understanding of what their symptoms mean to them and how they can express it,” she said.

Because of this, Gross and her colleagues relied on caregiver reports in the study.

The study included 1186 children under the age of 6 years, 670 of whom had tested positive for the virus at some point; 516 children had not been infected. Caregivers of all children completed a detailed survey about their children’s symptoms that had lasted for more than 4 weeks since the pandemic began, whether or not the problems were related to COVID-19 infection.

The researchers defined prolonged symptoms as those lasting more than 4 weeks and still present at the time of reporting. On average, infants and toddlers had symptoms that lingered for 10 months and nearly 17 months in preschool-aged children.

Building Clinician Awareness of Pediatric Long COVID

Using their findings, the researchers developed an age-specific tool to identify children likely to have long COVID. For infants and toddlers, symptoms like poor appetite and sleep problems were more common. For preschoolers, fatigue and dry cough were key signs. If a child’s score crossed a certain threshold, they were classified as “long COVID probable.”

Children with higher scores on the index “often had worse overall health, lower quality of life, and delays in development,” said Tanayott Thaweethai, PhD, associate director of Biostatistics Research and Engagement at Massachusetts General Hospital and an author of the study.

The instrument is currently applicable in research settings, not clinical practice, Thaweethai said.

“It’s not meant to be by itself a diagnostic tool,” Thaweethai said. “There very much could be children who are experiencing long COVID who may not present in exactly this way.”

Still, Thaweethai said he hopes pediatricians recognize its potential value.

“These are important signs that warrant further investigation to really determine if these symptoms for that child are attributable to a prior COVID infection,” he said.

Long COVID Rules for the Youngest

Current clinical guidelines for long COVID rely on research in adults. But across pediatric and adult medicine, the condition remains without a clinical biomarker.

“There isn’t a blood test right now or any specific test for diagnosing long COVID,” Gross said. “It really is diagnosed based on this history of prolonged symptoms.”

Gross suggested clinicians ask parents to track their children’s symptoms — documenting start date, duration, and severity.

While the study did not specifically evaluate the effects of vaccination on the risk for long COVID, Thaweethai said prior studies have suggested vaccines for the disease are protective against prolonged symptoms.

“There are essentially no treatments for long COVID, and vaccination can prevent COVID. Therefore, it’s one of our only tools for preventing long COVID,” he said.

“We really need to understand how long children are having these symptoms, how they wax and wane over time, how getting a reinfection with COVID changes the symptoms and the trajectory,” Gross said. “If we’re seeing these different symptoms in infants and toddlers and preschool aged children, what happens when those particular children enter school age? What happens to the symptoms that they have at that point? We don’t have the answers to those questions yet.”

As clinicians and researchers continue to untangle the complexities of long COVID in children, Yonker urged pediatricians to keep listening.

“Long COVID is a disease that impacts life,” she said. “Some of these kids have their lives impacted — if there’s school refusal, if they’re having post-exertional malaise and not able to participate in activities in school and learn to their potential.”

Lara Salahi is a health journalist based in Boston.

The experts quoted in this story did not report relevant disclosures. Some of the study authors not included in this story reported potential conflicts of interest, including serving on advisory boards, holding stock, and having affiliations with companies such as Pfizer, Blueprint Medicine, Gilead Sciences, and Merck, among others. The study was funded by the National Institutes of Health.