Long COVID-19 in Children and Adolescents: What Do We Know?

Roxana Tabakman

July 08, 2022

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Among scientists, the existence of long COVID-19 in children and adolescents has been the subject of debate. Two published studies have drawn attention to long COVID-19 signs and symptoms in these patients.

Published by a Mexican multidisciplinary group in Scientific Reports, the first study is a systematic review and meta-analysis. It identified mood symptoms as the most prevalent clinical manifestations of long COVID-19 in children and adolescents. These symptoms included sadness, tension, anger, depression, and anxiety (16.50%); fatigue (9.66%); and sleep disorders (8.42%).

The second study, LongCOVIDKidsDK, was conducted in Denmark. It compared 11,000 children younger than 14 years who had tested positive for COVID-19 with 33,000 children who had no history of COVID-19. The study was published in The Lancet Child and Adolescent Health.

Definitions Are Changing

In their meta-analysis, the researchers estimated the prevalence and counted signs and symptoms of long COVID-19, as defined by the United Kingdom's National Institute for Health and Care Excellence. Long COVID-19 was defined as the presence of one or more symptoms more than 4 weeks after SARS-CoV-2 infection. For search terms, the researchers used "COVID-19," "COVID," "SARSCOV-2," "coronavirus," "long COVID," "postCOVID," "PASC," "long-haulers," "prolonged," "post-acute," "persistent," "convalescent," "sequelae," and "postviral."

Of the 8373 citations returned by the search as of February 10, 2022, 21 prospective studies, two of them on preprint servers, met the authors' selection criteria. Those studies included a total of 80,071 children and adolescents younger than 18 years.

In the meta-analysis, the prevalence of long COVID-19 among children and adolescents was reported to be 25.24% (95% CI: 18.17 to 33.02; I2: 99.61%), regardless of whether the case had been asymptomatic, mild, moderate, severe, or serious. For patients who had been hospitalized, the prevalence was 29.19% (95% CI: 17.83 to 41.98; I2: 80.84%).

These numbers, while striking, are not the focus of the study, according to first author Sandra Lopez-Leon, MD, PhD, associate professor of pharmacoepidemiology at Rutgers University, New Brunswick, New Jersey. "It's important that we don't focus on that 25%," she told Medscape Medical News. "It's a disease that we're learning about, we're at a time when the definitions are still changing, and, depending on when it is measured, a different number will be given. The message we want to give is that long COVID-19 exists, it's happening in children and adolescents, and patients need this recognition. And also to show that it can affect the whole body."

The study showed that the children and adolescents who presented with SARS-CoV-2 infection were at higher risk of subsequent long dyspnea, anosmia/ageusia, or fever, compared with control persons.

In total, in the studies that were included, more than 40 long-term clinical manifestations associated with COVID-19 in the pediatric population were identified.

The most common symptoms among children aged 0 to 3 years were mood swings, skin rashes, and stomachaches. In 4- to 11-year-olds, the most common symptoms were mood swings, trouble remembering or concentrating, and skin rashes. In 12- to 14-year-olds, they were fatigue, mood swings, and trouble remembering or concentrating. These data are based on parent responses.

The list of signs and symptoms also includes headache, respiratory symptoms, cognitive symptoms (such as decreased concentration, learning difficulties, confusion, and memory loss), loss of appetite, and smell disorder (hyposmia, anosmia, hyperosmia, parosmia, and phantom smell).

In the studies, the prevalence of the following symptoms was less than 5%: hyperhidrosis, chest pain, dizziness, cough, myalgia/arthralgia, changes in body weight, taste disorder, otalgia (tinnitus, ear pain, vertigo), ophthalmologic symptoms (conjunctivitis, dry eye, blurred vision, photophobia, pain), dermatologic symptoms (dry skin, itchy skin, rashes, hives, hair loss), urinary symptoms, abdominal pain, throat pain, chest tightness, variations in heart rate, palpitations, constipation, dysphonia, fever, diarrhea, vomiting/nausea, menstrual changes, neurological abnormalities, speech disorders, and dysphagia.

The authors made it clear that the frequency and severity of these symptoms can fluctuate from one patient to another.

"The meta-analysis is important because it brings together 21 studies selected from more than 8000 articles ― and in them, a large number of children ― to study the most common manifestations of long COVID-19," Gabriela Ensinck, MD, head of the Infectious Diseases Department at the Víctor J. Vilela Children's Hospital in Rosario, Argentina, told Medscape. Ensinck did not participate in the study. "The important thing here is that long COVID-19 exists in pediatrics. And that it is a prolongation of signs or symptoms over time, a time for which there is no single definition."

"It's a snapshot of all the symptoms that can remain after COVID-19," Lopez-Leon explained. "The meta-analysis seeks to see if there's an association between having had COVID-19 and having the symptoms, but at no time does it speak of causality."

The prevalence of symptoms largely depends on the time since the onset of acute COVID-19. Most symptoms improve over time. In the studies that were included in the meta-analysis, the follow-up time varied between 1 and 13 months. For the authors, it would be important to understand what symptoms are associated with each period after the onset of infection.

Danish Parent Survey

The Danish study LongCOVIDKidsDK followed the World Health Organization criteria for long COVID-19 and included children and adolescents aged 0 to 14 years who received a diagnosis of COVID-19 and who experienced symptoms that lasted at least 2 months.

Between July 20, 2021, and September 15, 2021, a questionnaire was sent to 38,152 case patients and 147,212 control persons. Of this group, 10,997 (28.8%) case patients and 33,016 (22.4%) control persons answered the survey.

Children who had been diagnosed with SARS-CoV-2 infection were more likely to experience long-lasting symptoms than children who had never been diagnosed. Approximately one third of children with a positive SARS-CoV-2 test experienced symptoms that were not present before infection. Children who experienced long-lasting symptoms included 40% of children diagnosed with COVID-19 and 27% of control persons aged 0 to 3 years, 38% of case patients and 34% of control persons aged 4 to 11 years, and 46% of case patients and 41% of control persons aged 12 to 14 years.

Interestingly, those diagnosed with COVID-19 reported fewer psychologic and social problems than those in the control group. Among the oldest (aged 12 to 14 years), quality-of-life scores were higher and anxiety scores were lower for those who had tested positive for SARS-CoV-2.

More Information Needed

Given the diversity of symptoms in the meta-analysis and the LongCOVIDKidsDK study, a multidisciplinary approach is imperative. Lopez-Leon suggests that there is a need to raise awareness among parents, clinicians, researchers, and the health system about the conditions that can occur after COVID-19. Clinicians must better understand the sequelae to provide targeted care and treatment. The authors of the Danish study recommend establishing clinics for long COVID-19 with multispecialty care.

Maren J. Heilskov Rytter, PhD, associate professor of clinical medicine at the University of Copenhagen, Denmark, wrote an editorial about the Danish study. Until it is clarified whether SARS-CoV-2 does indeed cause persistent symptoms, she wrote, "it seems excessive and premature to establish specific multidisciplinary clinics for children with long COVID-19."

Rytter highlighted the difficulty of interpreting LongCOVIDKidsDK data, owing to recall bias, the failure to exclude other causes of symptoms in the cases analyzed, and the number of symptoms in the control persons. In addition, the data analyzed in Denmark are of limited clinical relevance, she said, given a greater presence of mild symptoms and, paradoxically, a higher quality of life.

She concluded, "In the majority of children with nonspecific symptoms after COVID-19, the symptoms presented are more likely to have been caused by something other than COVID-19, and if they are related to COVID-19, they are likely to go away over time."

Ensinck, who is co-author of the Argentine Ministry of Health's guide for long COVID-19 monitoring for children and adolescents and who represented the Infectious Diseases Committee of the Argentine Society of Pediatrics, highlighted another aspect of the problem. "What should be taken into account in these data is to see how much the confinement contributed. Children are the ones who suffered the most in the period in which schools were closed; they could not meet their peers, they had sick relatives, they felt fear...all this must be taken into account."

There is as yet no agreement on how to define and diagnose long COVID-19 in adults, a population that has been studied more closely. Part of the problem is that long COVID-19 has been linked to more than 200 symptoms, which can range in severity from inconvenient to debilitating, can last for months or years, and can recur, sometimes months after apparent recovery. Thus, there are still disparate answers to basic questions about the syndrome's frequency and its effects on vaccination, reinfection, and the latest variant of SARS-CoV-2.

Follow Roxana Tabakman of Medscape Spanish Edition on Twitter: @RoxanaTabakman.

This article has been translated from the Medscape Spanish edition.

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