Background Spain is one of the European countries most affected by the COVID-19 pandemic. Serological surveys are a valuable tool to assess the extent of the epidemic, given the existence of asymptomatic cases and little access to diagnostic tests. This nationwide population-based study aims to estimate the seroprevalence of SARS-CoV-2 infection in Spain at national and regional level.Methods 35 883 households were selected from municipal rolls using two-stage random sampling stratified by province and municipality size, with all residents invited to participate. From April 27 to May 11, 2020, 61 075 participants (75•1% of all contacted individuals within selected households) answered a questionnaire on history of symptoms compatible with COVID-19 and risk factors, received a point-of-care antibody test, and, if agreed, donated a blood sample for additional testing with a chemiluminescent microparticle immunoassay. Prevalences of IgG antibodies were adjusted using sampling weights and post-stratification to allow for differences in non-response rates based on age group, sex, and census-tract income. Using results for both tests, we calculated a seroprevalence range maximising either specificity (positive for both tests) or sensitivity (positive for either test). FindingsSeroprevalence was 5•0% (95% CI 4•7-5•4) by the point-of-care test and 4•6% (4•3-5•0) by immunoassay, with a specificity-sensitivity range of 3•7% (3•3-4•0; both tests positive) to 6•2% (5•8-6•6; either test positive), with no differences by sex and lower seroprevalence in children younger than 10 years (<3•1% by the point-of-care test). There was substantial geographical variability, with higher prevalence around Madrid (>10%) and lower in coastal areas (<3%). Seroprevalence among 195 participants with positive PCR more than 14 days before the study visit ranged from 87•6% (81•1-92•1; both tests positive) to 91•8% (86•3-95•3; either test positive). In 7273 individuals with anosmia or at least three symptoms, seroprevalence ranged from 15•3% (13•8-16•8) to 19•3% (17•7-21•0). Around a third of seropositive participants were asymptomatic, ranging from 21•9% (19•1-24•9) to 35•8% (33•1-38•5). Only 19•5% (16•3-23•2) of symptomatic participants who were seropositive by both the point-of-care test and immunoassay reported a previous PCR test.Interpretation The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas. Most PCR-confirmed cases have detectable antibodies, but a substantial proportion of people with symptoms compatible with COVID-19 did not have a PCR test and at least a third of infections determined by serology were asymptomatic. These results emphasise the need for maintaining public health measures to avoid a new epidemic wave.

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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After completing this course, the reader will be able to:1. Use patient age as only one consideration, along with tumor status and comorbidities, in deciding on treatment strategies for elderly colorectal cancer patients.2. Obtain and apply information regarding the medical, functional, mental, and social status of colorectal cancer elderly patients in order to make appropriate therapeutic decisions.This article is available for continuing medical education credit at CME.TheOncologist.com. CME CME ABSTRACTPurpose. To analyze differences in the therapeutic approach to and tumor-related mortality of young and elderly colorectal cancer (CRC) patients. Patients and Methods. This was a descriptive study of a retrospective cohort, based on administrative databases, of all patients with CRC diagnosed or treated in our institution. We extracted data on sociodemographic characteristics, comorbidity, type of cancer, type of treatment received, survival time, and cause of death. We compared differences between a young group (YG) (age <75 years) and an older group (OG) (age >75 years) and assessed the variables associated with receiving different therapeutic options (multivariate analysis) and with survival time (Cox proportional hazards models).Results. The study included 503 patients (YG, 320; OG, 183), with mean ages of 63.1 years in the YG and 81.8 years in the OG. No differences were observed between the groups in degree of differentiation, extension, tumor stage, or comorbidity. After adjustment for gender, comorbidity, and tumor localization and extension, YG patients were more likely than OG patients to receive surgery, radiotherapy, and chemotherapy and less likely to receive palliative care. After a median follow-up of 36.5 months, YG patients had a longer tumor-specific survival time than OG patients (36.41 months vs 26.05 months). After further adjustment, the YG had a lower tumor-specific mortality risk (hazard ratio, 0.66) than the OG.Conclusion. In comparison with younger patients, elderly CRC patients are undertreated, mainly because of their age and not because of their tumor type or comorbidity. Elderly patients have a significantly shorter tumor-specific survival time, partially because of this undertreatment.