Multisystem Inflammatory Syndrome in Children and SARS-CoV-2 variants: a two-year ambispective multicentric cohort study in Catalonia, Spain. (preprint)

Purpose Multisystem inflammatory syndrome in children (MIS-C) is a rare but severe disease temporarily related to SARS-CoV-2. We aimed to describe the epidemiological, clinical and laboratory findings of all the MIS-C cases diagnosed in children < 18 years-old in Catalonia (Spain) to study their trend throughout the pandemic.Methods Multicenter ambispective observational cohort study (April 2020-April 2022). Data were obtained from the COVID-19 Catalan surveillance system and from all the hospitals in Catalonia. We analyzed MIS-C cases regarding SARS-CoV-2 variants for demographics, symptoms, severity, monthly MIS-C incidence, ratio between MIS-C and accumulated COVID-19 cases, and associated rate ratios (RR).Results Among 555,848 SARS-CoV-2 infections, 152 children were diagnosed with MIS-C. Monthly MIS-C incidence was 4.1 (95%CI: 3.4–4.8) per 1,000,000 people, and 273 (95%CI: 230–316) per 1,000,000 SARS-CoV-2 infections (i.e., one case per 3,700 SARS-CoV-2 infections). During the Omicron period, MIS-C RR was 8.2 (95%CI: 5.7–11.7) per 1,000,000 SARS-CoV-2 infections, significantly lower (p < 0.001) than for previous variant periods, in all age groups. Median [IQR] age of MIS-C was 8 [4–11] years, 62.5% male, and 80.2% without comorbidities. Common symptoms were gastrointestinal findings (88.2%) and fever > 39oC (81.6%), nearly 40% had an abnormal echocardiography and 7% coronary aneurysm. Clinical manifestations and laboratory data were not different throughout the variant periods (p > 0.05).Conclusions The rate ratio between MIS-C cases and SARS-CoV-2 infections was significantly lower in the Omicron period for all the age groups, including those not vaccinated, suggesting that the variant could be the main factor for this shift in the MISC trend. Regardless of variant type, the patients had similar phenotypes and severity throughout the pandemic.

Fever without source as the first manifestation of SARS-CoV-2 infection in infants less than 90 days old. (preprint)

Fever without source (FWS) in infants is a frequent cause of consultation at the emergency department and the emergence of SARS-CoV-2 could affect the approach to those infants. The aim of this study is to define the clinical characteristics and rates of bacterial coinfections of infants < 90 days with FWS as the first manifestation of SARS-CoV-2 infection. This is a cross-sectional study of infants under 90 days of age with FWS and positive SARS-CoV2 PCR in nasopharyngeal swab/aspirate, attended at the emergency departments of 49 Spanish hospitals (EPICO-AEP cohort) from March 1st to June 26th, 2020. Three hundred and thirty-three  children with COVID-19 were included in EPICO-AEP. A total of 67/336 (20%) were infants less than 90 days old, and 27/67(40%) presented with FWS. Blood cultures were performed in 24/27(89%) and were negative in all but one (4%) who presented a Streptococcus mitis bacteremia. Urine culture was performed in 26/27(97%) children and was negative in all, except in two (7%) patients. Lumbar puncture was performed in 6/27(22%) cases, with no growth of bacteria. Two children had bacterial coinfections: 1 had UTI and bacteremia, and 1 had UTI. C-reactive was protein over 20 mg/L in two children (one with bacterial coinfection), and procalcitonin was normal in all. One child was admitted to the Pediatric Intensive Care Unit because of apnea episodes. No patients died. Conclusion: FWS was frequent in infants under 90 days of age with SARS-CoV-2 infection. Standardized markers to rule out bacterial infections remain useful in this population, and the outcome is generally good.