Interindividual clinical variability in the course of SARS-CoV-2 infection is immense. We report that at least 101 of 987 patients with life-threatening COVID-19 pneumonia had neutralizing IgG auto-Abs against IFN-ω (13 patients), the 13 types of IFN-α (36), or both (52), at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1,227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 were men. A B cell auto-immune phenocopy of inborn errors of type I IFN immunity underlies life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men.

Clinical outcome upon infection with SARS-CoV-2 ranges from silent infection to lethal COVID-19. We have found an enrichment in rare variants predicted to be loss-of-function (LOF) at the 13 human loci known to govern TLR3- and IRF7-dependent type I interferon (IFN) immunity to influenza virus, in 659 patients with life-threatening COVID-19 pneumonia, relative to 534 subjects with asymptomatic or benign infection. By testing these and other rare variants at these 13 loci, we experimentally define LOF variants in 23 patients (3.5%), aged 17 to 77 years, underlying autosomal recessive or dominant deficiencies. We show that human fibroblasts with mutations affecting this pathway are vulnerable to SARS-CoV-2. Inborn errors of TLR3- and IRF7-dependent type I IFN immunity can underlie life-threatening COVID-19 pneumonia in patients with no prior severe infection.

Significance There is growing evidence that preexisting autoantibodies neutralizing type I interferons (IFNs) are strong determinants of life-threatening COVID-19 pneumonia. It is important to estimate their quantitative impact on COVID-19 mortality upon SARS-CoV-2 infection, by age and sex, as both the prevalence of these autoantibodies and the risk of COVID-19 death increase with age and are higher in men. Using an unvaccinated sample of 1,261 deceased patients and 34,159 individuals from the general population, we found that autoantibodies against type I IFNs strongly increased the SARS-CoV-2 infection fatality rate at all ages, in both men and women. Autoantibodies against type I IFNs are strong and common predictors of life-threatening COVID-19. Testing for these autoantibodies should be considered in the general population.

Se ha descrito un nuevo síndrome inflamatorio multisistémico pediátrico vinculado a SARS-CoV-2. Este cuadro presenta una expresividad clínica variable y se asocia a infección activa o reciente por SARS-CoV-2. En este documento se revisa la literatura existente por parte de un grupo multidisciplinar de especialistas pediátricos. Posteriormente, se realizan recomendaciones sobre estabilización, diagnóstico y tratamiento de este síndrome.

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Background The role of SARS‐CoV‐2 as the cause of chilblains in children remains a matter of debate but it is important to elucidate it for patient isolation and contact tracing. We sought to define the etiology, clinical presentation, time course, and outcomes of children presenting to the emergency department (ED) with cutaneous manifestations shortly after the first pandemic peak of COVID‐19 in Spain. Methods A prospective, observational study in children <15 years of age evaluated for skin lesions in the EDs of three pediatric hospitals. Children underwent a comprehensive work‐up including tests for SARS‐CoV‐2 antibodies and polymerase chain reaction (PCR), and serology and PCR tests for other viruses and bacteria. A 1 month follow‐up visit was conducted. Results From April 14 through May 8, 2020, we enrolled 62 children. Of those, 34 had acro‐ischemic skin lesions and 28 had a variety of skin rashes. Overall, 40% of children had mild systemic symptoms. Children with chilblains were older, had pain more frequently and a more prolonged duration of skin lesions, while those with non‐specific rashes had fever more frequently. Lesions were resolved in 75% of children at follow up. Five patients demonstrated SARS‐CoV‐2 antibodies, and none tested positive with PCR. Three additional patients tested positive with PCR for rhinovirus, Mycoplasma pneumoniae and Chlamydia pneumoniae. Conclusions The number of ED visits for chilblains, which are rare in pediatrics, was high soon after the first peak of COVID‐19 in Spain. The disease course was self‐limited, outcomes were favorable, and the possibility of viral transmission was negligible as all patients tested negative for SARS‐CoV‐2 by PCR.

Introduction: COVID-19 has a less severe course in children. In April 2020, some children presented with signs of multisystem inflammation with clinical signs overlapping with Kawasaki disease (KD), most of them requiring admission to the pediatric intensive care unit (PICU). This study aimed to describe the prevalence and clinical characteristics of KD SARS-CoV-2 confirmed and negative patients during the pandemic in Spain.Material and Methods: Medical data of KD patients from January 1, 2018 until May 30, 2020 was collected from the KAWA-RACE study group. We compared the KD cases diagnosed during the COVID-19 period (March 1–May 30, 2020) that were either SARS-CoV-2 confirmed (CoV+) or negative (CoV–) to those from the same period during 2018 and 2019 (PreCoV).Results: One hundred and twenty-four cases were collected. There was a significant increase in cases and PICU admissions in 2020 (P-trend = 0.001 and 0.0004, respectively). CoV+ patients were significantly older (7.5 vs. 2.5 yr) and mainly non-Caucasian (64 vs. 29%), had incomplete KD presentation (73 vs. 32%), lower leucocyte (9.5 vs. 15.5 × 109) and platelet count (174 vs. 423 × 109/L), higher inflammatory markers (C-Reactive Protein 18.5vs. 10.9 mg/dl) and terminal segment of the natriuretic atrial peptide (4,766 vs. 505 pg/ml), less aneurysm development (3.8 vs. 11.1%), and more myocardial dysfunction (30.8 vs. 1.6%) than PreCoV patients. Respiratory symptoms were not increased during the COVID-19 period.Conclusion: The KD CoV+ patients mostly meet pediatric inflammatory multisystem syndrome temporally associated with COVID-19/multisystem inflammatory syndrome in children criteria. Whether this is a novel entity or the same disease on different ends of the spectrum is yet to be clarified.

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