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Children are not immune to the long-term effects of COVID-19. Joy Saha/Eyepix Group/Future Publishing via Getty Images
  • Researchers investigated the incidence of long-term symptoms in children following COVID-19 diagnosis.
  • They found that children who contracted SARS-CoV-2— the virus that causes COVID-19—were more likely to develop long-term symptoms than those who did not.
  • The researchers conclude that further studies are needed to understand how long COVID manifests in children and what their risk factors may be.

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Children are at risk of having COVID-19 as relatively few have been vaccinated, and other measures to reduce spread have been applied inconsistently or not at all in schools around the world.

As of June 23, 2022, the United States has reported nearly 13.7 million child COVID-19 cases, representing 18.8% of all cases. Child cases are also significantly higher than a year ago—with over 67,608 new cases in the week ending June 23rd/

After contracting SARS-CoV-2, some people go on to develop long COVID or a variety of symptoms that last at least two months and can’t be explained by other causes. However, until now, few studies have investigated long COVID in children.

Further research on the effects of COVID-19 in children could help inform public health practices.

Recently, researchers analyzed national healthcare data from Denmark to understand the long COVID risk among children ages 0-14 years old.

They found that children who had contracted SARS-CoV-2, the virus that causes COVID-19, were more likely to display long lasting symptoms following recovery than those who did not experience COVID-19.

The study was published in The Lancet.

For the study, the researchers used the Long COVIDKidsDK survey, a national cross-sectional study including children and adolescents who had been diagnosed with COVID-19 alongside undiagnosed controls of the same age and sex.

They examined data from 10,977 children ages 0-14 years old who tested positive for a SARS-CoV-2 infection, and 33,016 controls.

The data was collected between January 2020 and July 2021 and included surveys filled in by parents on the quality of life, somatic symptoms, and the 23 most common COVID-19 symptoms.

After analyzing the data, the researchers found that children who had contracted SARS-CoV-2 were more likely than controls to have symptoms lasting over two months.

Among those ages 0-3 years old, 40% of children diagnosed with COVID-19 — or 478 of 1,194 children— experienced symptoms longer than two months compared to 27% of controls— or 1,049 of 3,855 children.

The same was true for 38% of the children ages 4-11 years old who contracted COVID-19 compared to 34% of controls, and 46% of those in the 12-14 years old group compared to 41% of controls.

Different age groups reported different long COVID symptoms. The most common symptoms reported among the 0-3 age group were:

  • mood swings
  • rashes
  • stomach aches
  • cough
  • loss of appetite

Among those ages 4- 11, the most common symptoms were:

  • mood swings
  • trouble remembering or concentrating
  • rashes

And for those 12-14 years old, the most common symptoms were:

  • fatigue
  • mood swings
  • trouble remembering or concentrating

The researchers additionally noted that those ages 4-14 years old who had contracted SARS-CoV-2 reported better quality-of-life scores than controls. They noted that this may have stemmed from less “fear of the unknown” than controls.

When asked why some young children may develop long COVID, Dr. Stephen E. Hawes, professor and chair of the Department of Epidemiology at the University of Washington, who was not involved in the study, told Medical News Today that more research was needed to uncover risk factors for children.

“A number of factors have been identified as risk factors for long COVID in adults, including high viral load of coronavirus RNA, the presence of specific autoantibodies, reactivation of Epstein-Barr virus, and Type 2 diabetes,” he said.

“This study illustrates that all individuals, regardless of age, are at potential risk for long COVID. [C]hildren may have different longer-term manifestations of COVID, depending on their developmental stage, and the risk factors for the development of long COVID are less clear.”
— Dr. Stephen E. Hawes

Dr. Mark Hicar, associate professor at the Department of Pediatrics at the University at Buffalo, who was also not involved in the study, agreed that the reasons why some children develop long COVID remain unclear. He said:

“In our own clinic, we have seen siblings and even twins with different responses post-acute COVID, including variance in MIS-C cases. Even acute infections (COVID-19 or otherwise) may hit persons in the same family differently.”

“A combination of amount/area of inoculation, genetics, nutritional status, and history of recent infections or co-infections may all play a role in varying the presentation of an illness.”
— Dr. Mark Hicar

“In other post-viral syndromes, there are rare immune problems noted, but most of these currently are not explained well,” he added.

The researchers concluded that further research is needed to understand how long COVID arises in children.

When asked about the study’s limitations, Selina Kikkenborg Berg, study co-author and clinical professor at the Department of Medicine at the University of Copenhagen, noted that their study sample might not be representative of the whole population.

Prof. Berg added that the long COVID symptom list used might not include symptoms that emerged later in the pandemic.

Dr. Hawes also pointed out that as the study is a retrospective observational study, its results may be subject to a biased recall of events.

MNT asked Dr. Alison L. Miller, professor at the University of Michigan School of Public Health, who was not involved in the study, what these findings may mean for future healthcare strategies.

Dr. Miller said that they demonstrate the importance of coordinating care across daycares, schools, medical settings, and housing to ensure environments that encourage healthy child development.

“Schools and day care are important contexts for intervention, as they often see concerns emerging earlier than pediatricians and can provide support to families. Children who had COVID missed more school and day care than controls, and we know teachers are overburdened in addressing their needs,” she said.

“By connecting care across systems and also supporting the people working within those systems, we can build a better safety net to help children develop into healthy and productive adults,” she added.