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This study aims to assess the COVID-19 seroprevalence in HCW at the Hospital Central de la Defensa Gomez Ulla (HCDGU) (Madrid). From 27 April to 10 June 2020 nasopharyngeal swab and serum samples from employees were processed in order to evaluate their seroprevalence and infective situation. Employees were classified according to their exposure to SARS-CoV-2 infection as high, moderate, and low exposure groups (level 1, level 2, and level 3, respectively). A specific real-time polymerase chain reaction (RT-PCR) was run to diagnose each patient, whereas the qualitative detection of IgG antibodies to SARS-CoV-2 was performed by means of an immunoassay. In total, 2781 HCW were screened. From this sample, 30 employees (1.1%) were infected with SARS-CoV-2 and 450 (16.2%) were positive to SARS-CoV-2-IgG antibodies. The seroprevalence was higher in the high exposure group.The seroprevalence of antibodies against SARS-CoV-2 among employees without any COVID-19 training was higher than in those who received COVID-19 training (14.5% vs 18.6%, P = 0.035). The seroprevalence in military and civilian personnel in level 1 was 18.2% and 20.0%, respectively (P = 0.4616), while in level 2 it was 6.0% and 16.0% (P = 0.0008) and in level 3 it was 16.7% and 10.2% (P = 0.0315). The results from the present study have shown that the high exposure group and HCW not receiving specific training against COVID-19 showed higher seroprevalence. Furthermore, the military employees from this hospital presented low percentage of seroprevalence.

Background COVID19 is the novel respiratory illness caused by SARS-CoV-2. The presence of other potentially pathogenic microorganisms could worsen the prognosis of these patients. Aim: The study aims to describe coinfections in COVID-19 patients and contrast it between standard ward and critical care patients at Hospital Central de la Defensa Gomez Ulla (HCDGU). Methods A retrospective study was carried out of patients with COVID-19 confirmed with RTPCR admitted to the HCDGU from March 5, 2020 to May 7 of 2020. Findings Of a total of 703 patients with COVID-19, 75(10.7%) had other microbiologically confirmed infections: 9% (58/648) in standard ward patients and 31.5%(17/54) in critical care patients. In total 86 samples of the 75 patients presented some microorganism; clinically relevant bacteraemias, 50%, respiratory cultures, 32.6% and pneumococcal positive antigens, 17.4%. Conclusions We found a low frequency of microorganism coinfection in COVID-19 patients, however in critical care these coinfections increased considerably.

The surge of SARS‐CoV‐2 has challenged health systems worldwide and efficient tests to detect viral particles, as well as antibodies generated against them, are needed. Specificity, sensitivity, promptness or scalability are the main parameters to estimate the final performance, but rarely all of them match in a single test. We have developed SCOVAM, a protein microarray with several viral antigens (spike, nucleocapsid, main protease Nsp5) as capturing probes in a fluorescence immunoassay for COVID‐19 serological testing. SCOVAM depicts IgG and IgM antibody responses against each of these proteins of 22 individuals in a single microscope slide. It detects specific IgM (0.094 μg ml‐1) and IgG (~0.017 μg ml‐1) and is scalable and cost‐effective. We validated SCOVAM by comparing with a widely used chemiluminescent commercial serological test (n = 742). SCOVAM showed twice the sensitivity and allowed following seroconversion in a single assay. By analysing the prevalence 4 months later in a subset of 76 positive sera, we still detected 93.42% of positives, almost doubling the detection of the commercial assay. The higher sensitivity of SCOVAM is especially relevant to screen sera for convalescent plasma‐based treatments, high‐throughput antibody response monitoring after vaccination or evaluation of vaccine efficiency., This work has been funded by INTA’s internal budget and the Spanish Ministry of Science and Innovation grant nos. RTI2018‐094368‐B‐I00, and MDM‐2017‐0737 (Excelencia ‘María de Maeztu’ to Centro de Astrobiología). The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. DRG is funded by the ‘Programa de Atracción de Talento’ of local Government of Madrid. Centro Superior de Investigaciones Cientificas: project number 202020E079.

Coronavirus disease-19 (COVID19), the novel respiratory illness caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), is associated with severe morbidity and mortality. The aim of our study was to compare different immunoassays. We evaluated three immunochromatographic test (The StrongStep®SARS-CoV-2 IgG/IgM kit, AllTest COV-19 IgG/IgM kit, and Wondfo® SARS-CoV-2 Antibody) and two chemiluminescence immunoassays (CMIA) (Covid-19 VIRCLIA® IgM+IgA/IgG monotest and the Abbott SARS-CoV-2 IgG assay) in COVID-19 patients. The assays were performed using serum samples of three group patients, i.e., healthy controls, patients with SARS-CoV-2 PCR positive, and patients with SARS-CoV-2 PCR negative clinically diagnosed of COVID-19 infection. The detection percentages of IgG with the StrongStep® SARS-CoV-2 IgG/IgM kit and AllTest COV-19 IgG/IgM kit were similar in both groups (83.3% and 80.6%, respectively in group 2, p = 0.766) and (42.9% and 50.0%, respectively in group 3, p = 0.706). There were some differences on IgM detection between StrongStep® SARS-CoV-2 IgG/IgM kit and AllTest COV-19 IgG/IgM kit (11.1% and 30.6%, respectively in group 2, p = 0.042 and 0.0% and 28.6%, respectively in group 3, p = 0.031). The positive rate of IgG in group 2 is higher compared to group 3 with the two immunoassays tested. We observe the same positive rates of IgG with the two CMIA. Our study shows excellent performance of CMIA compared to immunochromatographic test and confirms its potential use in the diagnosis of the new SARS-CoV-2.