We determined and compared the humoral immune response in patients with severe (hospitalized) and mild (nonhospitalized) coronavirus disease 2019 (COVID-19). Patients with severe disease (n = 38) develop a robust antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including immunoglobulin G and immunoglobulin A antibodies. The geometric mean 50% virus neutralization titer is 1:240. SARS-CoV-2 infection was found in hospital personnel (n = 24), who developed mild symptoms necessitating leave of absence and self-isolation, but not hospitalization; 75% developed antibodies, but with low/absent virus neutralization (60% with titers <1:20). While severe COVID-19 patients develop a strong antibody response, mild SARS-CoV-2 infections induce a modest antibody response. Long-term monitoring will show whether these responses predict protection against future infections.

Background: The coronavirus disease (COVID-19) situation demands a lot from citizens, health care providers, and governmental institutions. Citizens need to cope with guidelines on social interaction, work, home isolation, and symptom recognition. Additionally, health care providers and policy makers have to cope with unprecedented and unpredictable pressure on the health care system they need to manage. By providing citizens with an app, they always have access to the latest information and can assess their own health. This data could be used to support policy makers and health care providers to get valuable insights in the regional distribution of infection load and health care consumption. Objective: The aim of this observational study is to assess people’s use of an app to support them with COVID-19 education, self-assessment, and monitoring of their own health for a 7-day period. In addition, we aim to assess the usability of this data for health care providers and policy makers by applying it to an interactive map and combining it with hospital data. The secondary outcomes of the study were user’s satisfaction with the information provided in the app, perceived usefulness of the app, health care providers they contacted, and the follow-up actions from this contact. Methods: This observational cohort study was carried out at the nonacademic teaching hospital “Elisabeth Twee Steden” (ETZ) in Tilburg, Netherlands. From April 1, 2020, onwards ETZ offered the COVID-19 education, self-assessment, and symptom tracking diary to their already existing app for patient education and monitoring. Results: Between April 1 and April 20, 2020, a total of 6194 people downloaded the app. The self-assessment functionality was used abundantly to check one’s health status. In total, 5104 people responded to the question about severe symptoms, from which 242 indicated to suffer from severe symptoms. A total of 4929 people responded to the question about mild symptoms, from which 3248 indicated to suffer from these. The data was successfully applied to an interactive map, displaying user demographics and health status. Furthermore, the data was linked to clinical data. App users were satisfied with the information in the app and appreciated the symptom diary functionality. In total, 102 users reached out to a health care provider, leading to 91 contacts. Conclusions: Our study demonstrated the successful implementation and use of an app with COVID-19 education, self-assessment, and a 7-day symptom diary. Data collected with the app were successfully applied to an interactive map. In addition, we were able to link the data to COVID-19 screening results from the hospital’s microbiology laboratory. This data could be used to support policy makers and health care providers to get valuable insights in the regional distribution of infection load and health care consumption. Trial Registration: Netherlands Trial Register NL8501; https://www.trialregister.nl/trial/8501

Knowledge of within-patient dynamics of resistance plasmids during outbreaks is important for understanding the persistence and transmission of plasmid-mediated antimicrobial resistance. During an outbreak of a Klebsiella pneumoniae carbapenemase-producing (KPC) K. pneumoniae, the plasmid and chromosomal dynamics of K. pneumoniae within-patients were investigated. During the outbreak, all K. pneumoniae isolates of colonized or infected patients were collected, regardless of their susceptibility pattern. A selection of isolates was short-read and long-read sequenced. A hybrid assembly of the short-and long-read sequence data was performed. Plasmid contigs were extracted from the hybrid assembly, annotated, and within patient plasmid comparisons were performed. Fifteen K. pneumoniae isolates of six patients were short-read whole-genome sequenced. Whole-genome multi-locus sequence typing revealed a maximum of 4 allele differences between the sequenced isolates. Within patients 1 and 2 the resistance gene- and plasmid replicon-content did differ between the isolates sequenced. Long-read sequencing and hybrid assembly of 4 isolates revealed loss of the entire KPC-gene containing plasmid in the isolates of patient 2 and a recombination event between the plasmids in the isolates of patient 1. This resulted in two different KPC-gene containing plasmids being simultaneously present during the outbreak. During a hospital outbreak of a KPC-producing K. pneumoniae isolate, plasmid loss of the KPC-gene carrying plasmid and plasmid recombination was detected within the isolates from two patients. When investigating outbreaks, one should be aware that plasmid transmission can occur and the possibility of within- and between-patient plasmid variation needs to be considered.

Background: The diagnostic accuracy of unsupervised self-testing with rapid antigen diagnostic tests (Ag-RDTs) is mostly unknown. We studied the diagnostic accuracy of a self-performed SARS-CoV-2 saliva and nasal Ag-RDT in the general population. Methods: This large cross-sectional study consecutively included unselected individuals aged $$\ge$$≥ 16 years presenting for SARS-CoV-2 testing at three public health service test sites. Participants underwent molecular test sampling and received two self-tests (the Hangzhou AllTest Biotech saliva self-test and the SD Biosensor nasal self-test by Roche Diagnostics) to perform themselves at home. Diagnostic accuracy of both self-tests was assessed with molecular testing as reference. Results: Out of 2819 participants, 6.5% had a positive molecular test. Overall sensitivities were 46.7% (39.3–54.2%) for the saliva Ag-RDT and 68.9% (61.6–75.6%) for the nasal Ag-RDT. With a viral load cut-off (≥ 5.2 log10 SARS-CoV-2 E-gene copies/mL) as a proxy of infectiousness, these sensitivities increased to 54.9% (46.4–63.3%) and 83.9% (76.9–89.5%), respectively. For the nasal Ag-RDT, sensitivities were 78.5% (71.1–84.8%) and 22.6% (9.6–41.1%) in those symptomatic and asymptomatic at the time of sampling, which increased to 90.4% (83.8–94.9%) and 38.9% (17.3–64.3%) after applying the viral load cut-off. In those with and without prior SARS-CoV-2 infection, sensitivities were 36.8% (16.3–61.6%) and 72.7% (65.1–79.4%). Specificities were > 99% and > 99%, positive predictive values > 70% and > 90%, and negative predictive values > 95% and > 95%, for the saliva and nasal Ag-RDT, respectively, in most analyses. Most participants considered the self-performing and result interpretation (very) easy for both self-tests. Conclusions: The Hangzhou AllTest Biotech saliva self Ag-RDT is not reliable for SARS-CoV-2 detection, overall, and in all studied subgroups. The SD Biosensor nasal self Ag-RDT had high sensitivity in individuals with symptoms and in those without prior SARS-CoV-2 infection but low sensitivity in asymptomatic individuals and those with a prior SARS-CoV-2 infection which warrants further investigation.

Objectives: This study was primarily conducted to evaluate clinical sensitivity and specificity of the SARS-CoV-2 rapid antigen test ‘BD Veritor System for Rapid Detection of SARS-CoV-2’ (VRD) compared to real time reverse transcriptase polymerase chain reaction (qRT-PCR). Furthermore, the VRD sensitivity for different Ct-value groups (Ct <20; Ct 20-25, Ct 25-30 and Ct ≥30) and different intervals since symptom onset (< 7 days; ≥ 7 days) were examined. Design: Prospective performance evaluation study. Setting: Municipal Health Service (GGD) COVID-19 test centres in West-Brabant, the Netherlands Participants: In order to evaluate clinical specificity, 352 symptomatic adults (≥18 years) who presented at a participating GGD test centre for a COVID-19 test between September 28 and October 7 2020 were included. In order to evaluate clinical sensitivity, 123 symptomatic adults (≥18 years) who were tested positive with qRT-PCR in a participating GGD test centre between September 26 and October 6 were included. Results: An overall clinical specificity of 100% (95%CI: 98.9%-100%) and sensitivity of 80.7% (95% CI: 73,2%-86,9%) was found for the VRD compared to qRT-PCR. Sensitivity was the highest for low Ct-value categories and for specimen obtained within the first days after disease onset. For specimen obtained within 7 days after onset of symptoms, the overall sensitivity was 91.0% (95% CI: 82,4%-96,3%) and 98,6% (95% CI: 92,3%-100%) for samples with qRT-PCR Ct-value beneath 30. Conclusion: The VRD is a promising diagnostic test for COVID-19 community screening for symptomatic individuals within 7 days after symptom onset in function of disease control. The clinical sensitivity was highest when viral load was high, which correlated with the duration of symptoms. Further research on practical applicability and the optimal position of the test within the current testing landscape is needed.