Prevalence, Symptoms and Duration of Post Acute Effects in SARS-CoV-2 Positive Children – a Nationwide Cohort Study

BACKGROUND: Most children have a mild course of acute COVID-19, but only a few mainly non-controlled studies with small sample size, have evaluated the long-term recovery from SARS-CoV-2 infection in children (‘long COVID’). METHODS: We conducted a nationwide cohort study of 37,522 children age 0-17 years with RT-PCR verified SARS-CoV-2 infection and a control group of 78,037 randomly selected children. An electronic questionnaire was sent to both groups of children from March 24th until May 9th 2021. RESULTS: Long COVID symptoms were reported by 12-51% of SARS-CoV-2 infected children. Among pre-school children, 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) were statistically significant symptoms of ‘long COVID’. 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 the SARS-CoV-2 infected. In most children ‘long COVID’ symptoms resolved within 1-5 months. CONCLUSIONS: This study provides new evidence of ‘long COVID’ symptoms in children. TRIAL REGISTRATION NUMBER: The study was approved by The Danish Health Data Authority and registered at Central Denmark region (# 1-16-02-621-20).