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Background: During the COVID-19 pandemic, disturbing images of ambulances unable to respond to the demands for prehospital assistance appeared from several parts of the world. In Denmark, however, a notion occurred that the demands for emergency medical assistance declined. The purpose of this study was to compare the patients' use of the Danish Emergency Medical Services (EMS) before and during the COVID-19 pandemic. Furthermore, we investigated the overall mortality of the ambulance population, the main reason for calling the emergency medical dispatch centre, and the diagnosis assigned to the admitted patients., Methods: The study was a nationwide registry-based cohort study based on the national prehospital medical records and the Danish National Patient Registry. The primary outcome was the requested number of ambulances. Secondary outcomes included the primary reason for contact with the dispatch centre (reflected by the dispatch criteria), patient mortality, and the diagnoses assigned to the patients transported to the hospital by ambulance during the COVID-19 pandemic in Denmark in March-December 2020. Comparisons were made using a similar period in 2019 before the pandemic., Results: In comparison with the baseline values before the pandemic, the total number of patients treated by the EMS was reduced by 4.5% during the COVID-19 pandemic. The number of patients transported to the hospital during the pandemic was similarly reduced by 3.5%. Compared with baseline values, fewer were patients hospitalised with respiratory diseases during the pandemic (a reduction of 53.3% from April 2019 to April 2020). Compared to the baseline period, there were significant increases in both the 48-h mortality (from 1.4% to 1.5%) and the 30-day mortality (from 4.9% to 5.4%) (p < 0.03 and p < 0.001, respectively), in patients hospitalised during the pandemic., Conclusion: During the first wave of the COVID-19 pandemic, the Danish EMS experienced an overall reduction in the requests for and the use of ambulances and, especially, in the number of patients admitted to hospitals for respiratory diseases. Despite the overall reduction in EMS requests, the mortality of the ambulance population increased, indicating that despite the reduced ambulance use, the prehospital population was more severely ill during the pandemic., (© 2024. The Author(s).)

This review summarizes current knowledge on post-acute sequelae of COVID-19 (PASC) and post-COVID-19 condition (PCC) in children and adolescents. A literature review was performed to synthesize information from clinical studies, expert opinions, and guidelines. PASC also termed Long COVID - at any age comprise a plethora of unspecific symptoms present later than 4 weeks after confirmed or probable infection with severe respiratory syndrome corona virus type 2 (SARS-CoV-2), without another medical explanation. PCC in children and adolescents was defined by the WHO as PASC occurring within 3 months of acute coronavirus disease 2019 (COVID-19), lasting at least 2 months, and limiting daily activities. Pediatric PASC mostly manifest after mild courses of COVID-19 and in the majority of cases remit after few months. However, symptoms can last for more than 1 year and may result in significant disability. Frequent symptoms include fatigue, exertion intolerance, and anxiety. Some patients present with postural tachycardia syndrome (PoTS), and a small number of cases fulfill the clinical criteria of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). To date, no diagnostic marker has been established, and differential diagnostics remains challenging. Therapeutic approaches include appropriate self-management as well as the palliation of symptoms by non-pharmaceutical and pharmaceutical strategies.    Conclusion: PASC in pediatrics present with heterogenous severity and duration. A stepped, interdisciplinary, and individualized approach is essential for appropriate clinical management. Current health care structures have to be adapted, and research was extended to meet the medical and psychosocial needs of young people with PASC or similar conditions. What is Known: • Post-acute sequelae of coronavirus 2019 (COVID-19) (PASC) - also termed Long COVID - in children and adolescents can lead to activity limitation and reduced quality of life. • PASC belongs to a large group of similar post-acute infection syndromes (PAIS). Specific biomarkers and causal treatment options are not yet available. What is New: • In February 2023, a case definition for post COVID-19 condition (PCC) in children and adolescents was provided by the World Health Organization (WHO), indicating PASC with duration of at least 2 months and limitation of daily activities. PCC can present as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). • Interdisciplinary collaborations are necessary and have been established worldwide to offer harmonized, multimodal approaches to diagnosis and management of PASC/PCC in children and adolescents., (© 2024. The Author(s).)

Background: Olfactory dysfunction associated with SARS-CoV-2 infection in children has not been verified by a validated olfactory test. We aimed to determine whether these complaints are objectifiable (test-based hyposmia), how often they occur during acute SARS-CoV-2 infection compared to other upper respiratory tract infections (URTI), as well as in children recovered from COVID-19 compared to children with long COVID., Methods: Olfactory testing (U-sniff test; hyposmia<8 points) and survey-based symptom assessments were performed in 434 children (5-17 years; 04/2021-06/2022). 186 symptom-free children served as controls. Of the children with symptoms of acute respiratory tract infection, SARS-CoV-2 PCR test results were positive in 45 and negative in 107 children (URTI group). Additionally, 96 children were recruited at least 4 weeks (17.6±15.2 weeks) after COVID-19, of whom 66 had recovered and 30 had developed long COVID., Results: Compared to controls (2.7%), hyposmia frequency was increased in all other groups (11-17%, p<0.05), but no between-group differences were observed. Only 3/41 children with hyposmia reported complaints, whereas 13/16 children with complaints were normosmic, with the largest proportion being in the long-COVID group (23%, p<0.05)., Conclusion: Questionnaires are unsuitable for assessing hyposmia frequency in children. Olfactory complaints and hyposmia are not specific for SARS-CoV-2 infection. The number of complaints in the long-COVID group could result from aversive olfactory perception, which is undetectable with the U-sniff test., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Purpose: Despite the need to generate valid and reliable estimates of protection levels against SARS-CoV-2 infection and severe course of COVID-19 for the German population in summer 2022, there was a lack of systematically collected population-based data allowing for the assessment of the protection level in real time., Methods: In the IMMUNEBRIDGE project, we harmonised data and biosamples for nine population-/hospital-based studies (total number of participants n = 33,637) to provide estimates for protection levels against SARS-CoV-2 infection and severe COVID-19 between June and November 2022. Based on evidence synthesis, we formed a combined endpoint of protection levels based on the number of self-reported infections/vaccinations in combination with nucleocapsid/spike antibody responses ("confirmed exposures"). Four confirmed exposures represented the highest protection level, and no exposure represented the lowest., Results: Most participants were seropositive against the spike antigen; 37% of the participants ≥ 79 years had less than four confirmed exposures (highest level of protection) and 5% less than three. In the subgroup of participants with comorbidities, 46-56% had less than four confirmed exposures. We found major heterogeneity across federal states, with 4-28% of participants having less than three confirmed exposures., Conclusion: Using serological analyses, literature synthesis and infection dynamics during the survey period, we observed moderate to high levels of protection against severe COVID-19, whereas the protection against SARS-CoV-2 infection was low across all age groups. We found relevant protection gaps in the oldest age group and amongst individuals with comorbidities, indicating a need for additional protective measures in these groups., (© 2023. The Author(s).)

Importance: Self- or health care worker (HCW)-collected nasal swab specimens are the preferred sampling method to perform rapid antigen testing for COVID-19, but it is debated whether throat specimens can improve test sensitivity., Objective: To compare the diagnostic accuracy of self- and HCW-collected nasal vs throat swab specimens for COVID-19 rapid antigen testing., Design, Setting, and Participants: This per-protocol multicenter randomized clinical trial was conducted from February 15 through March 25, 2022. The participants, individuals aged 16 years or older requesting a COVID-19 test for diagnostic or screening purposes, had 4 specimens collected for individual testing at 1 of 2 urban COVID-19 outpatient test centers in Copenhagen, Denmark., Interventions: Participants were randomized 1:1 to self-collected or HCW-collected nasal and throat swab specimens for rapid antigen testing. Additional HCW-collected nasal and throat swab specimens for reverse transcriptase-polymerase chain reaction (RT-PCR) were used as the reference standard., Main Outcomes and Measures: The primary outcome was sensitivity to diagnose COVID-19 of a self- vs HCW-collected nasal and throat specimen for rapid antigen testing compared with RT-PCR., Results: Of 2941 participants enrolled, 2674 (90.9%) had complete test results and were included in the final analysis (1535 [57.4%] women; median age, 40 years [IQR, 28-55 years]); 1074 (40.2%) had COVID-19 symptoms, and 827 (30.9%) were positive for SARS-CoV-2 by RT-PCR. Health care worker-collected throat specimens had higher mean sensitivity than HCW-collected nasal specimens for rapid antigen testing (69.4% [95% CI, 65.1%-73.6%] vs 60.0% [95% CI, 55.4%-64.5%]). However, a subgroup analysis of symptomatic participants found that self-collected nasal specimens were more sensitive than self-collected throat specimens for rapid antigen testing (mean sensitivity, 71.5% [95% CI, 65.3%-77.6%] vs 58.0% [95% CI, 51.2%-64.7%]; P < .001). Combining nasal and throat specimens increased sensitivity for HCW- and self-collected specimens by 21.4 and 15.5 percentage points, respectively, compared with a single nasal specimen (both P < .001)., Conclusions and Relevance: This randomized clinical trial found that a single HCW-collected throat specimen had higher sensitivity for rapid antigen testing for SARS-CoV-2 than a nasal specimen. In contrast, the self-collected nasal specimens had higher sensitivity than throat specimens for symptomatic participants. Adding a throat specimen to the standard practice of collecting a single nasal specimen could improve sensitivity for rapid antigen testing in health care and home-based settings., Trial Registration: ClinicalTrials.gov Identifier: NCT05209178.

Background: Patients with heart failure are vulnerable to the SARS-CoV-2 infection. However, limited evidence exists on the safety of the SARS-CoV-2 mRNA vaccines in this patient population. The objective of this study was to investigate the risk of all-cause mortality, worsening heart failure, venous thromboembolism, and myocarditis associated with the mRNA vaccines in patients with heart failure., Methods: Using Danish nationwide registries, 2 cohorts were constructed: (1) all prevalent heart failure patients in 2019 aged 40 to 95 years and (2) all prevalent heart failure patients in 2021 aged 40 to 95 years, who were vaccinated with either of the 2 mRNA vaccines (BNT162B2 or mRNA-1273). The patients in the 2 cohorts were matched 1:1 using exact exposure matching on age, sex, and duration of heart failure. To estimate standardized absolute risks, outcome-specific Cox regression analyses were performed., Results: The total study population comprised 101 786 patients. The median age of the study population was 74 years (interquartile range, 66-81). The standardized risk of all-cause mortality within 90 days was 2.23% (95% CI, 2.10%-2.36%) in the vaccinated cohort and 2.56% (95% CI, 2.43%-2.70%) in the unvaccinated cohort (90-day risk difference, -0.33% [95% CI, -0.52% to -0.15%]). The standardized risk of worsening heart failure within 90 days was 1.10% (95% CI, -1.01% to 1.19%) in the 2021 (vaccinated) cohort and 1.08% (95% CI, 0.99%-1.17%) in the 2019 (unvaccinated) cohort (risk difference, 0.02% [95% CI, -0.11% to 0.15%]). No significant differences were found regarding venous thromboembolism or myocarditis., Conclusions: Receiving an mRNA vaccine was not associated with an increased risk of worsening heart failure, myocarditis, venous thromboembolism, or all-cause mortality., Competing Interests: Disclosures Dr Biering-Sørensen is a Steering Committee member of the Amgen-financed GALACTIC-HF trial; Chief Investigator and Steering Committee Chair of the Sanofi Pasteur–financed NUDGE-FLU trial; Chief Investigator and Steering Committee Chair of the Sanofi Pasteur–financed DANFLU-1 trial; Chief Investigator and Steering Committee Chair of the Sanofi Pasteur–financed DANFLU-2 trial; Steering Committee member of the LUX-Dx TRENDS Evaluates Diagnostics Sensors in Heart Failure Patients Receiving Boston Scientific Investigational ICM System trial; advisory board member of Sanofi Pasteur, Amgen, and GSK; receives speaker honorarium from Novartis, Sanofi Pasteur, and GSK; and receives research grants from GE Healthcare and Sanofi Pasteur. Dr Torp-Pedersen reports grants from Bayer and Novo Nordisk, outside the submitted work. The other authors report no conflicts.

Background: Testing is critical for detecting SARS-CoV-2 infection, but the best sampling method remains unclear., Objectives: To determine whether nasopharyngeal swab (NPS), oropharyngeal swab (OPS) or saliva specimen collection has the highest detection rate for SARS-CoV-2 molecular testing., Methods: We conducted a randomised clinical trial at two COVID-19 outpatient test centres where NPS, OPS and saliva specimens were collected by healthcare workers in different orders for reverse transcriptase PCR testing. The SARS-CoV-2 detection rate was calculated as the number positive by a specific sampling method divided by the number in which any of the three sampling methods was positive. As secondary outcomes, test-related discomfort was measured with an 11-point numeric scale and cost-effectiveness was calculated., Results: Among 23 102 adults completing the trial, 381 (1.65%) were SARS-CoV-2 positive. The SARS-CoV-2 detection rate was higher for OPSs, 78.7% (95% CI 74.3 to 82.7), compared with NPSs, 72.7% (95% CI 67.9 to 77.1) (p=0.049) and compared with saliva sampling, 61.9% (95% CI 56.9 to 66.8) (p<0.001). The discomfort score was highest for NPSs, at 5.76 (SD, 2.52), followed by OPSs, at 3.16 (SD 3.16) and saliva samples, at 1.03 (SD 18.8), p<0.001 between all measurements. Saliva specimens were associated with the lowest cost, and the incremental costs per detected SARS-CoV-2 infection for NPSs and OPSs were US$3258 and US$1832, respectively., Conclusions: OPSs were associated with higher SARS-CoV-2 detection and lower test-related discomfort than NPSs for SARS-CoV-2 testing. Saliva sampling had the lowest SARS-CoV-2 detection but was the least costly strategy for mass testing., Trial Registration Number: NCT04715607., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: The study evaluates the effects on sero-immunity, health status and quality of life of children and adolescents after the upsurge of the Omicron variant in Germany., Methods: This multicenter cross-sectional study (IMMUNEBRIDGE Kids) was conducted within the German Network University Medicine (NUM) from July to October 2022. SARS-CoV-2- antibodies were measured and data on SARS-CoV-2 infections, vaccinations, health and socioeconomic factors as well as caregiver-reported evaluation on their children's health and psychological status were assessed., Results: 497 children aged 2-17 years were included. Three groups were analyzed: 183 pre-schoolchildren aged 2-4 years, 176 schoolchildren aged 5-11 years and 138 adolescents aged 12-18 years. Positive antibodies against the S- or N-antigen of SARS-CoV-2 were detected in 86.5% of all participants (70.0% [128/183] of pre-schoolchildren, 94.3% of schoolchildren [166/176] and 98.6% of adolescents [136/138]). Among all children, 40.4% (201/497) were vaccinated against COVID-19 (pre-schoolchildren 4.4% [8/183], schoolchildren 44.3% [78/176] and adolescents 83.3% [115/138]). SARS-CoV-2 seroprevalence was lowest in pre-school. Health status and quality of life reported by the parents were very positive at the time of the survey (Summer 2022)., Conclusion: Age-related differences on SARS-CoV-2 sero-immunity could mainly be explained by differences in vaccination rates based on the official German vaccination recommendations as well as differences in SARS-CoV-2 infection rates in the different age groups. Health status and quality of life of almost all children were very good independent of SARS-CoV-2 infection and/or vaccination., Trial Registration: German Registry for Clinical Trials Identifier Würzburg: DRKS00025546 (registration: 11.09.2021), Bochum: DRKS00022434 (registration:07.08.2020), Dresden: DRKS 00022455 (registration: 23.07.2020)., (© 2023. The Author(s).)

Background: Young children are among the most frequent patients at medical call centers, even though they are rarely severely ill. Respiratory tract symptoms are among the most prevalent reasons for contact in pediatric calls. Triage of children without visual cues and through second-hand information is perceived as difficult, with risks of over- and under-triage., Objective: To study the safety and feasibility of introducing video triage of young children with respiratory symptoms at the medical helpline 1813 (MH1813) in Copenhagen, Denmark, as well as impact on patient outcome., Methods: Prospective quality improvement study including 617 patients enrolled to video or standard telephone triage (1:1) from February 2019-March 2020. Data originated from MH1813 patient records, survey responses, and hospital charts. Primary outcome was difference in patients staying at home eight hours after the call. Secondary outcomes weas hospital outcome, feasibility and acceptability. Adverse events (intensive care unit admittance, lasting injuries, death) were registered. Logistic regression was used to test the effect on outcomes. The COVID-19 pandemic shut the study down prematurely., Results: In total, 54% of the included patients were video-triaged., and 63% of video triaged patients and 58% of telephone triaged patients were triaged to stay at home, (p = 0.19). Within eight and 24 hours, there was a tendency of fewer video-triaged patients being assessed at hospitals: 39% versus 46% (p = 0.07) and 41% versus 49% (p = 0.07), respectively. At 24 hours after the call, 2.8% of the patients were hospitalized for at least 12 hours. Video triage was highly feasible and acceptable (>90%) and no adverse events were registered., Conclusion: Video triage of young children with respiratory symptoms at a medical call center was safe and feasible. Only about 3% of all children needed hospitalization for at least 12 hours. Video triage may optimize hospital referrals and increase health care accessibility., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Gren et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The aim of this study was to provide information about immunity against COVID-19 along with risk factors and behavior among employees in day care facilities and preschools (DCS) in Denmark. In collaboration with the Danish Union of Pedagogues, during February and March 2021, 47,810 members were offered a point-of-care rapid SARS-CoV-2 antibody test (POCT) at work and were invited to fill in an electronic questionnaire covering COVID-19 exposure. Seroprevalence data from Danish blood donors (total Ig enzyme-linked immunosorbent assay [ELISA]) were used as a proxy for the Danish population. A total of 21,018 (45%) DCS employees completed the questionnaire and reported their POCT result {median age, 44.3 years (interquartile range [IQR], [32.7 to 53.6]); females, 84.1%}, of which 20,267 (96.4%) were unvaccinated and included in analysis. A total of 1,857 (9.2%) participants tested seropositive, significantly higher than a seroprevalence at 7.6% (risk ratio [RR], 1.2; 95% confidence interval [CI], 1.14 to 1.27) among 40,541 healthy blood donors (median age, 42 years [IQR, 28 to 53]; males, 51.3%). Exposure at work (RR, 2.9; 95% CI, 2.3 to 3.6) was less of a risk factor than exposure within the household (RR, 12.7; 95% CI, 10.2 to 15.8). Less than 25% of participants reported wearing face protection at work. Most of the participants expressed some degree of fear of contracting COVID-19 both at work and outside work. SARS-CoV-2 seroprevalence was slightly higher in DCS staff than in blood donors, but possible exposure at home was associated with a higher risk than at work. DCS staff expressed fear of contracting COVID-19, though there was limited use of face protection at work. IMPORTANCE Identifying at-risk groups and evaluating preventive interventions in at-risk groups is imperative for the ongoing pandemic as well as for the control of future epidemics. Although DCS staff have a much higher risk of being infected within their own household than at their workplace, most are fearful of being infected with COVID-19 or bringing COVID-19 to work. This represents an interesting dilemma and an important issue which should be addressed by public health authorities for risk communication and pandemic planning. This study design can be used in a strategy for ongoing surveillance of COVID-19 immunity or other infections in the population. The findings of this study can be used to assess the need for future preventive interventions in DCS, such as the use of personal protective equipment.

Background: Although severe COVID-19 in children is rare, those with certain pre-existing health conditions are more prone to severe disease. Monoclonal antibodies (mAbs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are potent antiviral agents that reduce adverse clinical outcomes in adults, but are commonly not approved for use in pediatric patients., Methods: We retrospectively evaluated mAb treatment in children <12 years of age or <40kg with SARS-CoV-2 infection between January 1, 2021, and March 7, 2022, in 12 tertiary care centers in 3 European countries., Results: We received data from 53 patients from Austria, Denmark and Germany. Median age was 5.4 years [0-13.8, interquartile range (IQR) = 6.2], and median body weight was 20 kg (3-50.1, IQR = 13). The most frequent SARS-CoV-2 variant in this study, if known, was Omicron, followed by Delta and Alpha. Pre-existing conditions included immunodeficiency, malignancy, hematologic disease, cardiac disease, chronic lung disease, chronic liver disease, kidney disease and diabetes. Forty-two patients received sotrovimab (79%), 9 casirivimab/imdevimab (17%) and 2 bamlanivimab (4%). All but 1 patient survived. Median duration of hospital stay was 3 days (0-56, IQR = 6). Seven patients required treatment in an intensive care unit, and 5 required high-flow nasal cannula treatment. Potential side effects included neutropenia (6/53, 11%), lymphopenia (3/53, 6%), nausea or vomiting (2/53, 4%), rise of alanine transaminase (1/53, 2%) and hypotonia (1/53, 2%)., Conclusions: MAb treatment was well tolerated by children in this cohort., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

This narrative review sums up data from the SARS-CoV-2-pandemia on preexisting disease/underlying conditions/comorbidities and risk factors in children for severe COVID-19 and MIS-C/PIMS-TS as well as hospitalization and mortality. Young infants and adolescents are at highest risk of hospital and PICU admission. Two or more comorbidities rather than single entities pose a risk for more severe courses of SARS-CoV-2 infection in children. Asthma and malignancy do not increase complication rates. MIS-C/PIMS-TS is not associated with any specific underlying disease., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

IntroductionSocio-economic and ethnic background have been discussed as possible risk factors for SARS-CoV-2 infections in children. Improved knowledge could lead to tailored prevention strategies and help improve infection control.AimWe aimed to identify risk factors for SARS-CoV-2 infections in children in the first and second wave of the pandemic.MethodsWe performed an observational population-based cohort study in children (6 months-18 years) scheduled for legally required preventive examination and their parents in a metropolitan region in Germany. Primary endpoint was the SARS-CoV-2 seroconversion rate during the study period. Risk factors assessed included age, pre-existing medical conditions, socio-economic factors and ethnicity.ResultsWe included 2,124 children and their parents. Seroconversion rates among children in all age groups increased 3-4-fold from June 2020 to February 2021. Only 24 of 58 (41%) seropositive children reported symptoms. In 51% of infected children, at least one parent was also SARS-CoV-2-positive. Low level of parental education (OR = 3.13; 95% CI: 0.72-13.69) non-significantly increased the risk of infection. Of the total cohort, 38.5% had a migration background, 9% of Turkish and 5% of Middle Eastern origin, and had the highest risk for SARS-CoV-2 infections (OR = 6.24; 95% CI: 1.38-28.12 and OR = 6.44 (95% CI: 1.14-36.45) after adjustment for other risk factors.ConclusionIn the second half of 2020, seroprevalence for SARS-CoV-2 in children increased especially in families with lower-socioeconomic status. Culture-sensitive approaches are essential to limit transmission and could serve as a blueprint for vaccination strategies.

Background: The purpose of this study was to assess whether influenza vaccination has an impact on the risk of coronavirus disease 2019 (COVID-19)., Methods: A cohort of 46 112 healthcare workers were tested for antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and filled in a survey on COVID-19 symptoms, hospitalization, and influenza vaccination., Results: The risk ratio of hospitalization due to SARS-CoV-2 for influenza vaccinated compared with unvaccinated participants was 1.00 for the seasonal vaccination in 2019/2020 (confidence interval, .56-1.78, P = 1.00). Likewise, no clinical effect of influenza vaccination on development of antibodies against SARS-CoV-2 was found., Conclusions: The present findings indicate that influenza vaccination does not affect the risk of SARS-CoV-2 infection or COVID-19., Competing Interests: Potential conflicts of interest. H. B. received lecture fee from BMS. F. F. received research grants from the Novo Nordisk Foundation and the Laerdal Foundation. M. G.-B. reports working as an unpaid chairman for the Committee for Transfusion Medicine, Danish Society for Clinical Immunology. A. D. K. received a research grant from the Danish Heart Foundation. T. B. reports grants for his institution from the Novo Nordisk Foundation, Simonsen Foundation, Lundbeck Foundation, Kai Foundation, and Erik and Susanna Olesen’s Charitable Fund. T. B. also reports the following: an unrestricted grant for his institution and working on the advisory board for GSK; an unrestricted grant for his institution, working as a principal investigator for a clinical trial, and working on the advisory board for Pfizer; working as a principal investigator for a clinical trial for Boehringer Ingelheim; an unrestricted grant for his institution, working as a principal investigator for a clinical trial, and working on the advisory board for Gilead Sciences; an unrestricted grant for his institution, working as a principal investigator, and working on the advisory board for MSD; working as a board member for Pentabase; working as a principal investigator for clinical trials for Roche, Novartis, and Kancera AB; and working on the advisory board for Janssen and Astra Zeneca. T. B. received consulting fees from GSK and Pfizer. T. B. held lectures for GSK, Pfizer, Gilead Sciences, Boehringer Ingelheim, Abbvie, and Astra Zeneca. T. B. received a donation of trial medication from Eli Lilly. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

The German government initiated the Network University Medicine (NUM) in early 2020 to improve national research activities on the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic. To this end, 36 German Academic Medical Centers started to collaborate on 13 projects, with the largest being the National Pandemic Cohort Network (NAPKON). The NAPKON's goal is creating the most comprehensive Coronavirus Disease 2019 (COVID-19) cohort in Germany. Within NAPKON, adult and pediatric patients are observed in three complementary cohort platforms (Cross-Sectoral, High-Resolution and Population-Based) from the initial infection until up to three years of follow-up. Study procedures comprise comprehensive clinical and imaging diagnostics, quality-of-life assessment, patient-reported outcomes and biosampling. The three cohort platforms build on four infrastructure core units (Interaction, Biosampling, Epidemiology, and Integration) and collaborations with NUM projects. Key components of the data capture, regulatory, and data privacy are based on the German Centre for Cardiovascular Research. By April 01, 2022, 34 university and 40 non-university hospitals have enrolled 5298 patients with local data quality reviews performed on 4727 (89%). 47% were female, the median age was 52 (IQR 36-62-) and 50 pediatric cases were included. 44% of patients were hospitalized, 15% admitted to an intensive care unit, and 12% of patients deceased while enrolled. 8845 visits with biosampling in 4349 patients were conducted by April 03, 2022. In this overview article, we summarize NAPKON's design, relevant milestones including first study population characteristics, and outline the potential of NAPKON for German and international research activities.Trial registration https://clinicaltrials.gov/ct2/show/NCT04768998 . https://clinicaltrials.gov/ct2/show/NCT04747366 . https://clinicaltrials.gov/ct2/show/NCT04679584., (© 2022. The Author(s).)

Background: People experiencing homelessness (PEH) and associated shelter workers may be at higher risk of infection with "Severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). The aim of this study was to determine the prevalence of SARS-CoV-2 among PEH and shelter workers in Denmark., Design and Methods: In November 2020, we conducted a nationwide cross-sectional seroprevalence study among PEH and shelter workers at 21 recruitment sites in Denmark. The assessment included a point-of-care test for antibodies against SARS-CoV-2, followed by a questionnaire. The seroprevalence was compared to that of geographically matched blood donors considered as a proxy for the background population, tested using a total Ig ELISA assay., Results: We included 827 participants in the study, of whom 819 provided their SARS-CoV-2 antibody results. Of those, 628 were PEH (median age 50.8 (IQR 40.9-59.1) years, 35.5% female) and 191 were shelter workers (median age 46.6 (IQR 36.1-55.0) years and 74.5% female). The overall seroprevalence was 6.7% and was similar among PEH and shelter workers (6.8% vs 6.3%, p = 0.87); and 12.2% among all participants who engaged in sex work. The overall participant seroprevalence was significantly higher than that of the background population (2.9%, p < 0.001). When combining all participants who reported sex work or were recruited at designated safe havens, we found a significantly increased risk of seropositivity compared to other participants (OR 2.23, 95%CI 1.06-4.43, p = 0.02). Seropositive and seronegative participants reported a similar presence of at least one SARS-CoV-2 associated symptom (49% and 54%, respectively)., Interpretations: The prevalence of SARS-CoV-2 antibodies was more than twice as high among PEH and associated shelter workers, compared to the background population. These results could be taken into consideration when deciding in which phase PEH are eligible for a vaccine, as part of the Danish national SARS-CoV-2 vaccination program rollout., Funding: TrygFonden and HelseFonden., (© 2022. The Author(s).)

Objectives: Antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are a key factor in protecting against coronavirus disease 2019 (COVID-19). We examined longitudinal changes in seroprevalence in healthcare workers (HCWs) in Copenhagen and the protective effect of antibodies against SARS-CoV-2., Methods: In this prospective study, screening for antibodies against SARS-CoV-2 (ELISA) was offered to HCWs three times over 6 months. HCW characteristics were obtained by questionnaires. The study was registered at ClinicalTrials.gov, NCT04346186., Results: From April to October 2020 we screened 44 698 HCWs, of whom 2811 were seropositive at least once. The seroprevalence increased from 4.0% (1501/37 452) to 7.4% (2022/27 457) during the period (p < 0.001) and was significantly higher than in non-HCWs. Frontline HCWs had a significantly increased risk of seropositivity compared to non-frontline HCWs, with risk ratios (RRs) at the three rounds of 1.49 (95%CI 1.34-1.65, p < 0.001), 1.52 (1.39-1.68, p < 0.001) and 1.50 (1.38-1.64, p < 0.001). The seroprevalence was 1.42- to 2.25-fold higher (p < 0.001) in HCWs from dedicated COVID-19 wards than in other frontline HCWs. Seropositive HCWs had an RR of 0.35 (0.15-0.85, p 0.012) of reinfection during the following 6 months, and 2115 out of 2248 (95%) of those who were seropositive during rounds one or two remained seropositive after 4-6 months. The 133 of 2248 participants (5.0%) who seroreverted were slightly older and reported fewer symptoms than other seropositive participants., Conclusions: HCWs remained at increased risk of infection with SARS-CoV-2 during the 6-month period. Seropositivity against SARS-CoV-2 persisted for at least 6 months in the vast majority of HCWs and was associated with a significantly lower risk of reinfection., (Copyright © 2021. Published by Elsevier Ltd.)

Background Little is known about how COVID-19 influenced engagement of citizen responders dispatched to out-of-hospital cardiac arrest (OHCA) by a smartphone application. The objective was to describe and analyze the Danish Citizen Responder Program and bystander interventions (both citizen responders and nondispatched bystanders) during the first COVID-19 lockdown in 2020. Methods and Results All OHCAs from January 1, 2020, to June 30, 2020, with citizen responder activation in 2 regions of Denmark were included. We compared citizen responder engagement for OHCA in the nonlockdown period (January 1, 2020, to March 10, 2020, and April 21, 2020, to June 30, 2020) with the lockdown period (March 11, 2020, to April 20, 2020). Data are displayed in the order lockdown versus nonlockdown period. Bystander cardiopulmonary resuscitation rates did not differ in the 2 periods (99% versus 92%; P =0.07). Bystander defibrillation (9% versus 14%; P =0.4) or return-of-spontaneous circulation (23% versus 23%; P =1.0) also did not differ. A similar amount of citizen responders accepted alarms during the lockdown (6 per alarm; interquartile range, 6) compared with the nonlockdown period (5 per alarm; interquartile range, 5) ( P =0.05). More citizen responders reported performing chest-compression-only cardiopulmonary resuscitation during lockdown compared with nonlockdown (79% versus 59%; P =0.0029), whereas fewer performed standardized cardiopulmonary resuscitation, including ventilations (19% versus 38%; P =0.0061). Finally, during lockdown, more citizen responders reported being not psychologically affected by attending an OHCA compared with nonlockdown period (68% versus 56%; P <0.0001). Likewise, fewer reported being mildly affected during lockdown (26%) compared with nonlockdown (35%) ( P =0.003). Conclusions The COVID-19 lockdown in Denmark was not associated with decreased bystander-initiated resuscitation in OHCAs attended by citizen responders.

The International Liaison Committee on Resuscitation initiated a continuous review of new, peer-reviewed published cardiopulmonary resuscitation science. This is the fifth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations; a more comprehensive review was done in 2020. This latest summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation task force science experts. Topics covered by systematic reviews in this summary include resuscitation topics of video-based dispatch systems; head-up cardiopulmonary resuscitation; early coronary angiography after return of spontaneous circulation; cardiopulmonary resuscitation in the prone patient; cord management at birth for preterm and term infants; devices for administering positive-pressure ventilation at birth; family presence during neonatal resuscitation; self-directed, digitally based basic life support education and training in adults and children; coronavirus disease 2019 infection risk to rescuers from patients in cardiac arrest; and first aid topics, including cooling with water for thermal burns, oral rehydration for exertional dehydration, pediatric tourniquet use, and methods of tick removal. Members from 6 International Liaison Committee on Resuscitation task forces have assessed, discussed, and debated the quality of the evidence, according to the Grading of Recommendations Assessment, Development, and Evaluation criteria, and their statements include consensus treatment recommendations or good practice statements. Insights into the deliberations of the task forces are provided in Justification and Evidence-to-Decision Framework Highlights sections. In addition, the task forces listed priority knowledge gaps for further research.

Background: COVID-19 is thought to be more prevalent among ethnic minorities and individuals with low socioeconomic status. We aimed to investigate the prevalence of SARS-CoV-2 antibodies during the COVID-19 pandemic among citizens 15 years or older in Denmark living in social housing (SH) areas., Methods: We conducted a study between January 8th and January 31st, 2021 with recruitment in 13 selected SH areas. Participants were offered a point-of-care rapid SARS-CoV-2 IgM and IgG antibody test and a questionnaire concerning risk factors associated with COVID-19. As a proxy for the general Danish population we accessed data on seroprevalence from Danish blood donors (total Ig ELISA assay) in same time period., Results: Of the 13,279 included participants, 2296 (17.3%) were seropositive (mean age 46.6 (SD 16.4) years, 54.2% female), which was 3 times higher than in the general Danish population (mean age 41.7 (SD 14.1) years, 48.5% female) in the same period (5.8%, risk ratios (RR) 2.96, 95% CI 2.78-3.16, p > 0.001). Seropositivity was higher among males (RR 1.1, 95% CI 1.05-1.22%, p = 0.001) and increased with age, with an OR seropositivity of 1.03 for each 10-year increase in age (95% CI 1.00-1.06, p = 0.031). Close contact with COVID-19-infected individuals was associated with a higher risk of infection, especially among household members (OR 5.0, 95% CI 4.1-6.2 p < 0,001). Living at least four people in a household significantly increased the OR of seropositivity (OR 1.3, 95% CI 1.0-1.6, p = 0.02) as did living in a multi-generational household (OR 1.3 per generation, 95% CI 1.1-1.6, p = 0.003). Only 1.6% of participants reported not following any of the national COVID-19 recommendations., Conclusions: Danish citizens living in SH areas of low socioeconomic status had a three times higher SARS-CoV-2 seroprevalence compared to the general Danish population. The seroprevalence was significantly higher in males and increased slightly with age. Living in multiple generations households or in households of more than four persons was a strong risk factor for being seropositive. Results of this study can be used for future consideration of the need for preventive measures in the populations living in SH areas., (© 2022. The Author(s).)

"Testing Denmark" is a national, large-scale, epidemiological surveillance study of SARS-CoV-2 in the Danish population. Between September and October 2020, approximately 1.3 million people (age >15 years) were randomly invited to fill in an electronic questionnaire covering COVID-19 exposures and symptoms. The prevalence of SARS-CoV-2 antibodies was determined by point-of care rapid test (POCT) distributed to participants' home addresses. In total, 318,552 participants (24.5% invitees) completed the study and 2,519 (0.79%) were seropositive. Of the participants with a prior positive PCR test ( n  = 1,828), 29.1% were seropositive in the POCT. Although seropositivity increased with age, participants 61 years and over reported fewer symptoms and were tested less frequently. Seropositivity was associated with physical contact with SARS-CoV-2 infected individuals (risk ratio [RR] 7.43, 95% CI: 6.57-8.41), particular in household members (RR 17.70, 95% CI: 15.60-20.10). A greater risk of seropositivity was seen in home care workers (RR 2.09, 95% CI: 1.58-2.78) compared to office workers. A high degree of adherence with national preventive recommendations was reported (e.g., >80% use of face masks), but no difference were found between seropositive and seronegative participants. The seroprevalence result was somewhat hampered by a lower-than-expected performance of the POCT. This is likely due to a low sensitivity of the POCT or problems reading the test results, and the main findings therefore relate to risk associations. More emphasis should be placed on age, occupation, and exposure in local communities. IMPORTANCE To date, including 318,522 participants, this is the largest population-based study with broad national participation where tests and questionnaires have been sent to participants' homes. We found that more emphasis from national and local authorities toward the risk of infection should be placed on age of tested individuals, type of occupation, as well as exposure in local communities and households. To meet the challenge that broad nationwide information can be difficult to gather. This study design sets the stage for a novel way of conducting studies. Additionally, this study design can be used as a supplementary model in future general test strategy for ongoing monitoring of COVID-19 immunity in the population, both from past infection and from vaccination against SARS-CoV-2, however, with attention to the complexity of performing and reading the POCT at home.

Objective: To assess the patterns in psychiatric admissions, referrals, and suicidal behavior before and during the COVID-19 pandemic., Methods: This study utilized health records from hospitals and Emergency Medical Services (EMS) covering 46% of the Danish population (n = 2,693,924). In a time-trend study, we compared the number of psychiatric in-patients, referrals to mental health services and suicidal behavior in years prior to the COVID-19 pandemic to levels during the first lockdown (March 11 - May 17, 2020), inter-lockdown period (May 18 - December 15, 2020), and second lockdown (December 16, 2020 - February 28, 2021)., Results: During the pandemic, the rate of psychiatric in-patients declined compared to pre-pandemic levels (RR = 0.95, 95% CI = 0.94 - 0.96, p < 0.01), with the largest decrease of 19% observed three weeks into the first lockdown. Referrals to mental health services were not significantly different (RR = 1.01, 95% CI = 0.92 - 1.10, p = 0.91) during the pandemic; neither was suicidal behavior among hospital contacts (RR = 1.04, 95% CI = 0.94 - 1.14, p = 0.48) nor EMS contacts (RR = 1.08, 95% CI = 1.00 - 1.18, p = 0.06). Similar trends were observed across nearly all age groups, sexes, and types of mental disorders examined. In the age group <18, an increase in the rate of psychiatric in-patients (RR = 1.11, 95% CI = 1.07 - 1.15, p < 0.01) was observed during the pandemic; however, this did not exceed the pre-pandemic, upwards trend in psychiatric hospitalizations in the age group <18 (p = 0.78)., Conclusion: The COVID-19 pandemic has been associated with a decrease in psychiatric hospitalizations, while no significant change was observed in referrals to mental health services and suicidal behavior. Psychiatric hospitalizations among children and adolescents increased during the pandemic; however, this appears to be a continuation of a pre-pandemic trend., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The International Liaison Committee on Resuscitation initiated a continuous review of new, peer-reviewed published cardiopulmonary resuscitation science. This is the fifth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations; a more comprehensive review was done in 2020. This latest summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation task force science experts. Topics covered by systematic reviews in this summary include resuscitation topics of video-based dispatch systems; head-up cardiopulmonary resuscitation; early coronary angiography after return of spontaneous circulation; cardiopulmonary resuscitation in the prone patient; cord management at birth for preterm and term infants; devices for administering positive-pressure ventilation at birth; family presence during neonatal resuscitation; self-directed, digitally based basic life support education and training in adults and children; coronavirus disease 2019 infection risk to rescuers from patients in cardiac arrest; and first aid topics, including cooling with water for thermal burns, oral rehydration for exertional dehydration, pediatric tourniquet use, and methods of tick removal. Members from 6 International Liaison Committee on Resuscitation task forces have assessed, discussed, and debated the quality of the evidence, according to the Grading of Recommendations Assessment, Development, and Evaluation criteria, and their statements include consensus treatment recommendations or good practice statements. Insights into the deliberations of the task forces are provided in Justification and Evidence-to-Decision Framework Highlights sections. In addition, the task forces listed priority knowledge gaps for further research., (Copyright © 2021 European Resuscitation Council, American Heart Association, Inc. and International Liaison Committee on Resuscitation. Published by Elsevier B.V. All rights reserved.)

The win odds is a distribution-free method of comparing locations of distributions of two independent random variables. Introduced as a method for analyzing hierarchical composite endpoints, it is well suited to be used in the analysis of ordinal scale endpoints in COVID-19 clinical trials. For a single outcome, we provide power and sample size calculation formulas for the win odds test. We also provide an implementation of the win odds analysis method for a single ordinal outcome in a commonly used statistical software to make the win odds analysis fully reproducible.

The German Society of Pneumology initiated the AWMFS1 guideline Post-COVID/Long-COVID. In a broad interdisciplinary approach, this S1 guideline was designed based on the current state of knowledge.The clinical recommendation describes current post-COVID/long-COVID symptoms, diagnostic approaches, and therapies.In addition to the general and consensus introduction, a subject-specific approach was taken to summarize the current state of knowledge.The guideline has an expilcit practical claim and will be continuously developed and adapted by the author team based on the current increase in knowledge., Competing Interests: Eine Übersicht der Interessenkonflikte findet sich im Internet unter http://awmf.org; AWMF-Registriernummer 020-027., (Thieme. All rights reserved.)

Introduction: The reference test to evaluate patients with suspected respiratory virus infection is a real-time reverse transcription-polymerase chain reaction (RT-PCR) from a nasopharyngeal swab (NPS). However, other specimen collection methods such as an oropharyngeal swab (OPS) or saliva specimen are also used for SARS-CoV-2 testing during the ongoing COVID-19 pandemic. However, it remains unclear if rates of SARS-CoV-2 detection differ between sampling methods. This study will compare the rates of SARS-CoV-2 detection by saliva, OPS, and NPS sampling in a public setting., Methods: Individuals referred for outpatient SARS-CoV-2 testing will be invited to participate in a prospective clinical study. They will have saliva, OPS and NPS specimens collected that will be analysed separately for SARS-CoV-2 RNA by RT-PCR. The rate of SARS-CoV-2 detection in saliva, OPS and NPS will be compared using a logistic regression mixed-effect model analysis. A sample of 19,110 participants is required at an expected 1.5% test-positive rate in order to detect a 25.6% difference. The total sample size will be adjusted as the test-positive rate changes., Conclusions: This study will provide evidence for the optimal site of specimen collection to detect SARS-CoV-2. The results may help guide the health authorities., Funding: This is an investigator-initiated trial based on an unrestricted grant from the Novo Nordisk Foundation and the Aage og Johanne Louis-Hansens Fond. The foundations have had no say in the decisions on study design or reporting., Trial Registration: ClinicalTrials.gov (ID: NCT04715607)., (Articles published in the DMJ are “open access”. This means that the articles are distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits any non-commercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.)

Background: In emergencies, such as the COVID-19 pandemic, there is an increased need for contact with emergency medical services (EMS), and call volume might surpass capacity. The Copenhagen EMS operates two telephone line the 1-1-2 emergency number and the 1813 medical helpline. A separate coronavirus support track was implemented on the 1813 medical helpline and a web-based self-triage (web triage) system was created to reduce non-emergency call volume. The aim of this paper is to present call volume and the two measures implemented to handle the increased call volume to the Copenhagen EMS., Methods: This is a cross sectional observational study. Call volume and queue time is presented in the first month of the COVID-19 pandemic (27th of February 2020 to 27 th of march) and compared to the equivalent month from the year before (2019). Descriptive statistics are conducted on call volumes and queue times and spearman's rank correlation test are performed to test correlation between web triage and call volume., Results: Total EMS call volume increase by 23.3% between 2019 and 2020 (92.670 vs. 114,250). The 1-1-2 emergency line total call volume increase by 4.4% (8,4942 vs. 8,870) and the 1813 medical helpline increased by 25.1% (84.176 vs. 105.380). The coronavirus support track handled 21,063 calls. The 1813 medical helpline queue time was a mean of 02 minutes and 23 seconds (CI: 2.22-2.25) in 2019 and 12 minutes and 2 seconds (CI 11:55-12:09) in 2020 (P < 0.001). The web triage was used 10,894 times. No correlation between call volume and web triage usage was seen., Conclusions: In the first month of the ongoing COVID-19 pandemic a significant increase in call volume was observed in the 1813 medical helpline compared to 2019. A large number of calls were handled by the additional coronavirus track and diverted away from the regular tracks of the 1813 medical helpline. This likely contributed to mitigating increased call volumes and queue times. The web triage was widely used but no significant correlation was seen with 1813 medical helpline call volume. Other EMS organizations can learn from this to enhance capacity in a future epidemics.

Background: Health-care workers are thought to be highly exposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We aimed to investigate the prevalence of antibodies against SARS-CoV-2 in health-care workers and the proportion of seroconverted health-care workers with previous symptoms of COVID-19., Methods: In this observational cohort study, screening was offered to health-care workers in the Capital Region of Denmark, including medical, nursing, and other students who were associated with hospitals in the region. Screening included point-of-care tests for IgM and IgG antibodies against SARS-CoV-2. Test results and participant characteristics were recorded. Results were compared with findings in blood donors in the Capital Region in the study period., Findings: Between April 15 and April 23, 2020, we screened 29 295 health-care workers, of whom 28 792 (98·28%) provided their test results. We identified 1163 (4·04% [95% CI 3·82-4·27]) seropositive health-care workers. Seroprevalence was higher in health-care workers than in blood donors (142 [3·04%] of 4672; risk ratio [RR] 1·33 [95% CI 1·12-1·58]; p<0·001). Seroprevalence was higher in male health-care workers (331 [5·45%] of 6077) than in female health-care workers (832 [3·66%] of 22 715; RR 1·49 [1·31-1·68]; p<0·001). Frontline health-care workers working in hospitals had a significantly higher seroprevalence (779 [4·55%] of 16 356) than health-care workers in other settings (384 [3·29%] of 11 657; RR 1·38 [1·22-1·56]; p<0·001). Health-care workers working on dedicated COVID-19 wards (95 [7·19%] of 1321) had a significantly higher seroprevalence than other frontline health-care workers working in hospitals (696 [4·35%] of 15 983; RR 1·65 [1·34-2·03]; p<0·001). 622 [53·5%] of 1163 seropositive participants reported symptoms attributable to SARS-CoV-2. Loss of taste or smell was the symptom that was most strongly associated with seropositivity (377 [32·39%] of 1164 participants with this symptom were seropositive vs 786 [2·84%] of 27 628 without this symptom; RR 11·38 [10·22-12·68]). The study is registered at ClinicalTrials.gov, NCT04346186., Interpretation: The prevalence of health-care workers with antibodies against SARS-CoV-2 was low but higher than in blood donors. The risk of SARS-CoV-2 infection in health-care workers was related to exposure to infected patients. More than half of seropositive health-care workers reported symptoms attributable to COVID-19., Funding: Lundbeck Foundation., (Copyright © 2020 Elsevier Ltd. All rights reserved.)