Children who have had COVID-19 can experience symptoms of long COVID for at least two months, Danish researchers report today.
The study, published in *The Lancet Child & Adolescent Health*, used national level sampling of children from age 0-14, in Denmark and matched COVID-19 positive cases with a control group of children who have not been infected with the virus.
Professor Selina Kikkenborg Berg, Copenhagen University Hospital, said although most studies of long COVID in young people have focused on adolescents this study also included younger children who had tested positive for COVID-19 between January 2020 and July 2021.
Surveys were sent to parents or guardians of the children and responses were received for almost 11,000 children with a positive COVID-19 test result. These were matched by age and sex to more than 33,000 children who had never tested positive for the virus.
The surveys asked about the 23 most common symptoms of long COVID in children, which had been identified by the Long COVID Kids Rapid Survey of January 2021 and used the World Health Organization definition of long COVID as symptoms lasting more than two months.
The most commonly reported symptoms among children up to three years old were mood swings, rashes, and stomach aches, while among 4-11 years old the most commonly reported symptoms were mood swings, trouble remembering or concentrating, and rashes. Those aged 12-14 years reported mainly fatigue, mood swings, and trouble remembering or concentrating.
All age groups of children who’d had COVID-19 were more likely to experience at least one symptom for two months or longer than the control group. In the 0-3 years age group 40% of children diagnosed with COVID-19 (478 of 1,194 children) experienced symptoms for longer than two months, compared to 27% of controls (1,049 of 3,855 children).
In the 4-11 years age group, the ratio was 38% of cases (1,912 of 5,023 children) compared to 34% of controls (6,189 of 18,372 children), and for the 12-14 years age group, 46% of cases (1,313 of 2,857 children) compared to 41% of controls (4,454 of 10,789 children) experienced long-lasting symptoms.
The types of non-specific symptoms associated with long COVID are often experienced by otherwise healthy children – headache, mood swings, abdominal pain, and fatigue are all symptoms of common ailments that children experience that are unrelated to COVID-19.
However, this study showed that children who had had the virus were more likely to experience long-lasting symptoms than those who had never had a positive diagnosis, which, suggest the authors, that these were long COVID.
This is supported by about one third of children in the positive group experiencing symptoms that were not present before the SARS-CoV-2 infection.
Prof Kikkenborg Berg said: “The opportunity to undertake such research is rapidly closing as the vast majority of children have now had a COVID-19 infection, for example 58% of children in Denmark had lab confirmed infection between December 2021 and February 2022.
“Knowledge of long-term symptom burden in SARS-CoV-2 positive children is essential to guide clinical recognition, parental caregiving, and societal decisions about isolation, lockdown, non-pharmaceutical interventions, and vaccine strategies.
“Our findings align with previous studies of long COVID in adolescents showing that, although the chances of children experiencing long COVID is low, especially compared to control groups, it must be recognised and treated seriously.”
She said more research is needed to better understand these symptoms and the long-term consequences of the pandemic on children.
She and fellow authors said there were some limitations to the study, including a long recall period between diagnosis and taking the survey and public testing for COVID-19 was only available from August 2020, which meant some children in the control group could have had undetected asymptomatic infections.
Kikkenborg Berg S, Palm P, Nygaard U et al. Long COVID symptoms in SARS-CoV-2-positive children aged 0–14 years and matched controls in Denmark (LongCOVIDKidsDK): a national, cross-sectional study. * The Lancet Child & Adolescent Health* 23 June 2022
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