Long COVID - the physical and mental health of children and non-hospitalised young people 3 months after SARS-CoV-2 infection; a national matched cohort study (The CLoCk) Study.

Introduction: We describe post-COVID symptomatology in a national sample of 11-17-year-old children and young people (CYP) with PCR-confirmed SARS-CoV-2 infection compared to test-negative controls.Methods and analysis: A cohort study of test-positive (n=3,065) and age-, sex- and geographically-matched test-negative CYP (n=3,739) completed detailed questionnaires 3 months post-test.Results: At PCR-testing, 35.4% of test-positives and 8.3% of test-negatives had any symptoms whilst 30.6% and 6.2%, respectively, had 3+ symptoms. At 3 months post-testing, 66.5% of test-positives and 53.3% of test-negatives had any symptoms, whilst 30.3% and 16.2%, respectively, had 3+ symptoms. Latent class analysis identified two classes, characterised by “few” or “multiple” symptoms. This latter class was more frequent among test-positives, females, older CYP and those with worse pre-test physical and mental health.Discussion: Test-positive CYP had a similar symptom profile to test-negative CYP but with higher prevalence of single and, particularly, multiple symptoms at PCR-testing and 3 months later.