Long COVID symptoms and duration in SARS-CoV-2 positive children - a nationwide cohort study

Abstract

Most children have a mild course of acute COVID-19. Only few mainly non-controlled studies with small sample size have evaluated long-term recovery from SARS-CoV-2 infection in children. The aim of this study was to evaluate symptoms and duration of 'long COVID' in children. A nationwide cohort study of 37,522 children aged 0-17 years with RT-PCR verified SARS-CoV-2 infection (response rate 44.9%) and a control group of 78,037 children (response rate 21.3%). An electronic questionnaire was sent to all children from March 24th until May 9th, 2021. Symptoms lasting > 4 weeks were common among both SARS-CoV-2 children and controls. However, SARS-CoV-2 children aged 6-17 years reported symptoms more frequently than the control group (percent difference 0.8%). The most reported symptoms among pre-school children were fatigue Risk Difference (RD) 0.05 (CI 0.04-0.06), loss of smell RD 0.01 (CI 0.01-0.01), loss of taste RD 0.01 (CI 0.01-0.02) and muscle weakness RD 0.01 (CI 0.00-0.01). Among school children the most significant symptoms were loss of smell RD 0.12 (CI 0.12-0.13), loss of taste RD 0.10 (CI 0.09-0.10), fatigue RD 0.05 (CI 0.05-0.06), respiratory problems RD 0.03 (CI 0.03-0.04), dizziness RD 0.02 (CI 0.02-0.03), muscle weakness RD 0.02 (CI 0.01-0.02) and chest pain RD 0.01 (CI 0.01-0.01). Children in the control group experienced significantly more concentration difficulties, headache, muscle and joint pain, cough, nausea, diarrhea and fever than SARS-CoV-2 infected. In most children 'long COVID' symptoms resolved within 1-5 months.

Conclusions: Long COVID in children is rare and mainly of short duration.

What is known: • There are increasing reports on 'long COVID' in adults. • Only few studies have evaluated the long-term recovery from COVID-19 in children, and common for all studies is a small sample size (median number of children included 330), and most lack a control group.

What is new: • 0.8% of SARS-CoV-2 positive children reported symptoms lasting >4 weeks ('long COVID'), when compared to a control group. • The most common 'long COVID' symptoms were fatigue, loss of smell and loss of taste, dizziness, muscle weakness, chest pain and respiratory problems. • These 'long COVID' symptoms cannot be assigned to psychological sequelae of social restrictions. • Symptoms such as concentration difficulties, headache, muscle- and joint pain as well as nausea are not 'long COVID' symptoms. • In most cases 'long COVID' symptoms resolve within 1-5 months.

Keywords: COVID-19; Children; Long COVID; Long-term recovery; Sars-CoV-2.

Fig. 1

CONSORT Flow chart of study participants

Fig. 2

Prevalence of symptoms lasting > 4 weeks. Percentage of SARS-CoV-2 infected children reporting at least one symptom lasting > 4 weeks (red bars) or reporting no symptoms (blue bars). Data are presented as total population of SARS-CoV-2 infected children (upper panel) and by gender (girls, middle panel; boys, lower panel)

Fig. 3

Heatmap illustrating reported symptoms lasting for > 4 weeks by SARS-CoV-2 infected children (upper panel) and controls (lower panel). The numbers represent percentage of children reporting the given symptom by one-year age groups

Fig. 4

Comparison of symptom prevalence in SARS-CoV-2 infected children and the control group indicated by risk differences (RD) with 95% confidence interval and p-values. Panel A: comparison of children 0–17 years. Panel B: Sub-group comparison of pre-school children, 0–5 years. Panel C: Sub-group comparison of school children, 6–17 years

Fig. 5

Duration of symptoms from date of positive RT-PCR SARS-CoV-2 test until date for questionnaire completion by 1-year age groups. In the upper panel, the dark green bars represent percentage of children who reported that their symptoms had not resolved at time of questionnaire completion. The follow-up time of these children´s on-ongoing symptoms is illustrated in the lower panel