Some clusters of children with a multisystem inflammatory syndrome associated with SARS-CoV-2 infection (MIS-C) have been reported. We describe the epidemiological and clinical features of children with MIS-C in Spain. MIS-C is a potentially severe condition that presents in children with recent SARS-CoV-2 infection.

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ObjectivesTo evaluate the performance of oral saliva swab (OSS) reverse transcription PCR (RT-PCR) compared with RT-PCR and antigen rapid diagnostic test (Ag-RDT) on nasopharyngeal swabs (NPS) for SARS-CoV-2 in children.DesignCross-sectional multicentre diagnostic study.SettingStudy nested in a prospective, observational cohort (EPICO-AEP) performed between February and March 2021 including 10 hospitals in Spain.PatientsChildren from 0 to 18 years with symptoms compatible with Covid-19 of ≤5 days of duration were included. Two NPS samples (Ag-RDT and RT-PCR) and one OSS sample for RT-PCR were collected.Main outcomePerformance of Ag-RDT and RT-PCR on NPS and RT-PCR on OSS sample for SARS-CoV-2.Results1174 children were included, aged 3.8 years (IQR 1.7–9.0); 73/1174 (6.2%) patients tested positive by at least one of the techniques. Sensitivity and specificity of OSS RT-PCR were 72.1% (95% CI 59.7 to 81.9) and 99.6% (95% CI 99 to 99.9), respectively, versus 61.8% (95% CI 49.1 to 73) and 99.9% (95% CI 99.4 to 100) for the Ag-RDT. Kappa index was 0.79 (95% CI 0.72 to 0.88) for OSS RT-PCR and 0.74 (95% CI 0.65 to 0.84) for Ag-RDT versus NPS RT-PCR.ConclusionsRT-PCR on the OSS sample is an accurate option for SARS-CoV-2 testing in children. A less intrusive technique for younger patients, who usually are tested frequently, might increase the number of patients tested.

The massive number of infected individuals who have to be tested for SARS-CoV-2 has attracted the attention to novel diagnostic approaches, focusing on symptom-based screening. 1 Some countries have emerged national testing policies, but a large number of positive children do not report any of the included symptoms in those guidelines. 2 This study aimed to analyse symptoms/signs associated with SARS-CoV-2 infection among symptomatic children screened for COVID-19 and define clinical phenotypes that could differentiate COVID-19 from other infections. We performed a cross-sectional multicentre study, nested in a prospective, observational cohort, EPICO-AEP (Epidemiological Study of COVID-19 in Children of the Spanish Society of Paediatric). 3 Eligible participants were children <18 years old with symptoms compatible with SARS-CoV-2 infection lasting ≤5 days (Table 1) 1 attended at 10 emergency departments in Spain, from 2 March to 15 June 2021 (third epidemic wave in Spain; >70% SARS-CoV-2 isola-