BACKGROUND:The World Health Organization declared the outbreak of coronavirus disease to be a public health emergency of international concern on January 30, 2020. The first SARS-CoV-2 infection was subsequently detected in Luxembourg on February 29, 2020. Representative population-based data, including asymptomatic individuals for assessing the viral spread and immune response was, however, lacking worldwide. METHODS:Using a panel-based method, we recruited a representative sample of the Luxembourgish population based on age, gender and residency for testing for SARS-CoV-2 infection and antibody status in order to define prevalence irrespective of clinical symptoms. Participants were contacted via email to fill an online questionnaire before biosampling at local laboratories. Participants provided information related to clinical symptoms, epidemiology, socioeconomic and psychological assessments and underwent biosampling, rRT-PCR testing and serology for SARS-CoV-2. RESULTS:A total of 1862 individuals were included for our representative sample of the general Luxembourgish population. We detected an ongoing SARS-CoV-2 infection based on rRT-PCR in 5 participants. h Four of the SARS-CoV-2 infected participants were oligosymptomatic and one was asymptomatic. Overall, 35 participants (1.97%) had developed a positive IgG response, of whom 11 self-reported to have previously received a positive rRT-PCR diagnosis of SARS-CoV-2 infection. Our data indicate a prevalence of 0.3% for active SARS-CoV-2 infection in the Luxembourgish population between 18 and 79 years of age. CONCLUSIONS:Luxembourgish residents show a low rate of acute infections after 7 weeks of confinement and present with an antibody profile indicative of a more recent immune response to SARS-CoV-2. All infected individuals were oligo-or asymptomatic. Bi-weekly follow-up visits over the next 2 months will inform about the viral spread by oligo-and asymptomatic carriers and the individual changes in the immune profile.

clinical and dermoscopic examination and 14 (82.4%) were misclassified by OCT.With additional use of OCT, the PPV increased from 95Á6% (without OCT) to 99Á2% (109 of 110) with OCT. The decrease in the percentage of misclassifications was not significant, but a study with enough power to detect differences in this order of magnitude would require a much larger sample size.In another prospective study, the PPV of an OCT diagnosis that was made with high confidence was only 80%, but the BCC prevalence in that study was also lower (58Á2%) than in the present study (95Á6%). The PPV depends on prevalence and becomes lower if prevalence decreases. 8 The use of OCT in addition to clinical and dermoscopic examination may reduce the risk of misclassification of non-BCC lesions as BCC; however, this study also shows that in cases of high clinical and dermoscopic suspicion of BCC, this risk is already very low. The gain from additional use of OCT in patients with high clinical suspicion of BCC must be balanced against the financial investment required for the purchase of an OCT device and training of OCT users.

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Background Infections with SARS-CoV-2 have a pronounced impact on the gastrointestinal tract and its resident microbiome. Clear differences between severe cases of infection and healthy individuals have been reported, including the loss of commensal taxa. We aimed to understand if microbiome alterations including functional shifts are unique to severe cases or a common effect of COVID-19. We used high-resolution systematic multi-omic analyses to profile the gut microbiome in asymptomatic-to-moderate COVID-19 individuals compared to a control group. Results We found a striking increase in the overall abundance and expression of both virulence factors and antimicrobial resistance genes in COVID-19. Importantly, these genes are encoded and expressed by commensal taxa from families such as Acidaminococcaceae and Erysipelatoclostridiaceae, which we found to be enriched in COVID-19-positive individuals. We also found an enrichment in the expression of a betaherpesvirus and rotavirus C genes in COVID-19-positive individuals compared to healthy controls. Conclusions Our analyses identified an altered and increased infective competence of the gut microbiome in COVID-19 patients.