Symptomatology of long COVID among children below 14 years of age in Denmark

In a recent study published in The Lancet Child and Adolescent Health, researchers investigated long coronavirus disease (COVID) symptoms among severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected Danish children below 14 years of age.

Study: Long COVID symptoms in SARS-CoV-2-positive children aged 0–14 years and matched controls in Denmark (LongCOVIDKidsDK): a national, cross-sectional study. Image Credit: New Africa/Shutterstock


Children are at an increased risk of COVID 2019 (COVID-19) and post-COVID-19 (long COVID) syndrome due to the lack of authorized vaccines for children, scare recommendations for pediatric vaccinations, low vaccine uptake, and social distancing difficulties among children. Knowledge of long COVID among children is vital to guide the identification and management of COVID-19 and long COVID by setting up multi-disciplinary long COVID clinics.

About the study

In the present cross-sectional and nationwide LongCOVIDKidsDK study, researchers investigated the long COVID symptomatology and its impact on quality of life and absence from schools and daycare facilities among SARS-CoV-2-infected children aged <14 years in Denmark.

The study comprised a 1:4 ratio of SARS-CoV-2 infected Danish children (cases) with diagnoses confirmed by polymerase chain reaction (PCR) between 1 January 2020 and 12 July 2021 (cases) and age- and sex-matched controls. The cases were identified from the Danish COVID-19 database, and the controls were identified from the Danish Civil Registration System.

Proxy reports were obtained by surveys filled out by mothers/fathers/legal guardians of children below 14 years of age. They included the children’s somatic symptoms inventory-24 (CSSI-24) and pediatric quality of life inventory (PedsQL) to obtain data on child well-being and overall health. Additionally, the survey forms included ancillary questions on 23 long COVID symptoms most commonly reported in the long COVID kids' rapid survey conducted in January 2021.

The symptoms included chest pain, stomach ache, fatigue, mood swings, headache, muscular or joint pain, concentration and/or recall difficulties, appetite loss, cough, dizziness, sore throat, rashes, fever, nausea, breathing difficulties, palpitations, and extreme pallor. Other symptoms such as skin discoloration, sensitivity to light, dark circles under the eyes, and chapping of lips were also included.

Quality of life was assessed for dimensions such as emotional, physical, social, emotional, and school or daycare functioning over the previous month. Only participants with a recall period of >2 months were included in the study. Data were analyzed using logistic regression and descriptive statistics. The differences were considered clinically significant if the Hedges’ g scores were >0.2.  

The PubMed database was searched on 4 January 2021 for studies investigating long COVID among children, resulting in one paper including a case description of five children in Sweden. Further, Google Scholar was searched, and one preprint study from Italy, including 75 long COVID children without controls, was found.

Furthermore, the website mentioned ongoing studies which reported a high prevalence of long-lasting symptoms. Still, the studies were small, did not include the youngest age groups, and lacked control groups and laboratory-confirmed SARS-CoV-2 reports. Few studies reported symptoms to be also highly prevalent among controls. Moreover, most studies used a cutoff of four weeks for long COVID, whereas the World Health Organization (WHO), in October 2021, defined long COVID to be lasting eight weeks.


A total of 10997 responses (28.8%) and 33016 responses (22.4%) were obtained for cases and controls, respectively, between 20 July 2021 and 15 September 2021. The mean age of the cases and controls was ten years and 10.6 years, respectively. Long COVID was present in 31% (n = 427) children aged 0 to 3 years, 26.5% (n=1505) children aged 4 to 11 years, and 32·5% (n = 1077) of children aged 12 to 14 years.

The most commonly reported symptoms in the 0 to 3 years age group were rashes, mood swings, stomach aches, appetite loss, and cough. In the 4 to 11 years age group, concentration difficulties, recall difficulties, rashes, and mood swings, were most frequent. In the 12 to 14 years age group, mood swings, concentration difficulties, recall difficulties, and fatigue were most frequently reported. With an increase in symptom duration, the number of children with the symptoms reduced.

The odds of >1 symptom lasting for >2 months were greater among cases than controls for children below three years of age [odds ratio (OR) 1.8], for those aged between four and 11 years (OR 1.2) and for those aged between 12 and 14 years (OR 1.2). Significant differences were noted in the CSSI-24 scores between the case group children and the controls; however, the differences were not relevant clinically.

Contrastingly, differences with clinical relevance were noted in the PedsQL scores for the emotional dimension among cases and controls for children four to 11 years of age (scores were 80 and 75 for cases and controls, respectively) and for children aged 12 to 14 years (scores were 90 and 85 for cases and controls, respectively). Likewise, PedsQL scores for the social dimension were greater for cases (median scores were 100 and 95 for cases and controls, respectively) for children aged 12 to 14 years.

Among children aged 13 months to three years, the number of children reported having ≥16 days of sick leave among cases (28.4%) was higher among cases compared to controls (18.4%). The corresponding proportions of children reporting ≥16 days of absence from school or daycare were also higher among cases (23.9%) compared to controls (14.1%).

Similar results were observed for children aged four to 11 years (cases vs. controls 7.0% vs. 3.8% for ≥16 days sick leave; and 6.1% vs. 3.3% for ≥16 days of school or daycare absence). The corresponding proportions for the 12 to 14 years age group were 9.0% vs 5.2%; and 6.5% vs 5.0%, respectively. The findings indicated that across all ages, cases reported more sick leave and a greater number of absent days for schools or daycare facilities in the previous year compared to controls.


Overall, the study findings showed that long-term symptoms were more prevalent among SARS-CoV-2-positive children compared to controls aged below 14 years, with better quality-of-life scores in relation to social and emotional functioning among cases of older age (four to 11 years and 12 to 14 years). However, the clinical differences on a population level seemed to be small.

Journal reference:
  • Long COVID symptoms in SARS-CoV-2-positive children aged 0–14 years and matched controls in Denmark (LongCOVIDKidsDK): a national, cross-sectional study. Selina Kikkenborg Berg, et al. Lancet Child Adolesc Health. doi:

Posted in: Medical Science News | Medical Research News | Disease/Infection News

Tags: Adolescent Health, Breathing, Chest Pain, Children, Coronavirus, Coronavirus Disease COVID-19, Cough, covid-19, Fatigue, Fever, Headache, Joint Pain, Laboratory, Nausea, Pain, Polymerase, Polymerase Chain Reaction, Respiratory, SARS, SARS-CoV-2, Severe Acute Respiratory, Severe Acute Respiratory Syndrome, Skin, Sore Throat, Stomach, Syndrome, Throat, Vaccine

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Pooja Toshniwal Paharia

Dr. based clinical-radiological diagnosis and management of oral lesions and conditions and associated maxillofacial disorders.

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