SARS-CoV-2 Antigen Rapid Detection Tests: test performance during the COVID-19 pandemic and the impact of COVID-19 vaccination (preprint)

IntroductionDuring the COVID-19 pandemic, SARS-CoV-2 antigen rapid detection tests (RDTs) emerged as point-of-care diagnostics in addition to the RT-qPCR as the gold standard for SARS-CoV-2 diagnostics. Facing the course of the COVID-19 pandemic to an endemic characterised by several SARS-CoV-2 virus variants of concern (VOC) and an increasing public COVID-19 vaccination rate the aim of the study was to investigate the long-term test performance of SARS-CoV-2 RDT in large-scale, clinical screening use during and its influencing factors, above all SARS-CoV-2 VOC and COVID-19 vaccination. MethodsIn a prospective performance assessment conducted at a single centre tertiary care hospital, RDTs from three manufacturers (NADAL(R), Panbio, MEDsan(R)) were compared to RT-qPCR among individuals aged [≥] 6 month. The evaluation involved the determination of standardised viral load from oropharyngeal swabs as well as the evaluation of their influencing factors, especially the COVID-19 vaccination, for detecting SARS-CoV-2 in a clinical point-of-care environment spanning from 12 November 2020 to 30 June 2023 among patients, staff, and visitors of the hospital. ResultsAmong the 78,798 RDT/RT-qPCR tandems analysed, 2,016 (2.6%) tandems tested positive for SARS-CoV-2, with an overall sensitivity of 34.5% (95% CI 32.4-36.6%). A logistic regression revealed that typical COVID-19 symptoms significantly declined over the course of the study and throughout the COVID-19 pandemic, and that among the vaccinated, significantly fewer presented with an infection exhibiting typical symptoms. The employed lasso regression model indicated that only higher viral load and typical COVID-19 symptoms significantly increase the likelihood of a positive RDT result in the case of a SARS-CoV-2 infection directly. ConclusionOur findings indicate that only viral load and COVID-19 symptoms directly influence RDT performance while the obtained effects of COVID-19 vaccination and Omicron VOC both reducing RDT performance were mediated by these two factors. RDTs remain an adequate diagnostic tool for detecting SARS-CoV-2 in individuals showing respiratory symptoms. RDTs show promise beyond SARS-CoV-2, proving adaptable for detecting other pathogens like Influenza and RSV, highlighting their ongoing importance in infection control and prevention efforts.

Examination of Influenza A Infection Rate, Its Determinants, and Seasonal Influenza Vaccine Effectiveness in the Post-COVID-19 Pandemic Era (preprint)

BackgroundIn the context of the COVID-19 pandemic, a pronounced wave of Influenza A occurred in the 2022/23 winter season under generally relaxed post-pandemic non-pharmaceutical preventive measures. AimThis study aimed to investigate the Influenza A infection rate, factors influencing its occurrence and seasonal Influenza vaccine effectiveness on seroconversion in the post-COVID-19 pandemic era. MethodsThe seroconversion of Anti-Influenza-A-Nucleoprotein/Matrix IgG was investigated in 402 healthcare workers (HCWs) during the winter season of 2022/2023 (23 May 2022 to 11 May 2023). The participants provided a serum sample and completed a study questionnaire both before and after the seasonal Influenza A wave (24 October 2022 to 8 January 2023). The levels of a vaccine-independent Anti-Influenza-A-Nucleoprotein/Matrix IgG were measured using the SERION ELISA classic Influenza A IgG assay, with a 2-fold increase as indicative of seroconversion after asymptomatic or symptomatic influenza infection. ResultsAmong the participants, 20.6% (95% CI 17.0-24.9%; 83/402) showed seroconversion. The multivariate logistic regression analysis revealed that the age category of [≥] 45 years (p=0.03) and regular patient contact (p=0.02) significantly influenced seroconversion. However, the factors male gender, BMI, smoking, household size, seasonal Influenza vaccination, and SARS-CoV-2 infection during the Influenza A season were not significantly associated with seroconversion. The effectiveness of the 2022/23 seasonal Influenza vaccine on seroconversion induced by Influenza infection was 22.6% (95% CI -17.1-50.6%). ConclusionDuring the initial Influenza A season following the COVID-19 pandemic, approximately 20% of HCWs contracted an Influenza A infection. This highlights a potential risk and a significant asymptomatic or symptomatic infection rate posing a theoretical risk for intrahospital transmission chains and nosocomial infections.

The relationship between mental health, sleep quality, and the immunogenicity of COVID-19 vaccinations (preprint)

Sleep modulates the immune response and sleep loss can reduce the immunogenicity of certain vaccinations. Vice versa immune responses impact sleep. We aimed to investigate the influence of mental health and sleep quality on the immunogenicity of COVID-19 vaccinations and, conversely, of COVID-19 vaccinations on sleep quality. The prospective CoVacSer study monitored mental health, sleep quality, and Anti-SARS-CoV-2-Spike IgG titres in a cohort of 1,082 healthcare workers from the 29th of September 2021 to the 19th of December 2022. Questionnaires and blood samples were collected before, 14 days, and three months after the third COVID-19 vaccination. In 154 participants the assessments were also conducted before and 14 days after the fourth COVID-19 vaccination. Healthcare workers with psychiatric disorders had slightly lower Anti-SARS-CoV-2-Spike IgG levels before the third COVID-19 vaccination. However, this effect was mediated by higher median age and body mass index in this subgroup. Antibody titres following the third and fourth COVID-19 vaccination (booster vaccinations) were not significantly different between subgroups with and without psychiatric disorders. Sleep quality did not affect the humoral immunogenicity of the COVID-19 vaccinations. Moreover, the COVID-19 vaccinations did not impact self-reported sleep quality. Our data suggests that in a working population neither mental health nor sleep quality relevantly impact the immunogenicity of COVID-19 vaccinations and that COVID-19 vaccinations are not a precipitating factor for insomnia. The findings from this large-scale real-life cohort study will inform clinical practice regarding the recommendation of COVID-19 booster vaccination for individuals with mental health and sleep problems.

Inability to work following COVID-19 vaccination among healthcare workers - an important aspect for future booster vaccinations (preprint)

Background COVID-19 vaccination is a key prevention strategy to reduce the spread and severity of SARS-CoV-2 infections, especially among highly exposed healthcare workers (HCWs). However, vaccine-related inability to work among HCWs could overstrain healthcare systems. Methods This study examined sick leave and intake of pro re nata (PRN) medication after the first, second and third COVID-19 vaccination in HCWs. Subgroup analyses were performed for different vaccines, gender, healthcare professions, and for HCWs aged at least 30 years. Data was collected by using an electronic questionnaire. Findings Among 1,704 HCWs enrolled, in total 595 (34{middle dot}9%) HCWs were on sick leave following at least one COVID 19 vaccination, leading to a total number of 1,550 sick days. Both the absolute sick days and the rate of HCWs on sick leave significantly increased with each subsequent vaccination. Comparing BNT162b2mRNA and mRNA-1273 the difference in sick leave was not significant after the second dose, but mRNA-1273 induced a significantly longer and more frequent sick leave after the third. Interpretation A considerable number of HCWs have been on sick leave after COVID-19 vaccination, staff absences increase with each additional dose, depend on the vaccine, and vary between HCWs' gender, and profession. In the light of further COVID-19 infection waves and booster vaccinations, there is a risk of additional staff shortages due to post-vaccination inability to work, which could acutely overload healthcare systems and jeopardise patient care. These findings will aid further vaccination campaigns to minimise the impact of staff absences on the healthcare system.

Clinical accuracy of SARS-CoV-2 rapid antigen testing in screening children and adolescents in comparison to RT-qPCR, November 2020 to September 2022 (preprint)

Background Rapid antigen detection tests (RDT) are an easily accessible, feasible, inexpensive, and point of care method in SARS-CoV-2 diagnostics - established in adults as well as in children and adolescents. Despite this, large-scale data of clinical performance in the paediatric population especially regarding the influence of SARS-CoV-2 virus variants of concern (VOC) and COVID-19 vaccination on test accuracy is rare. Methods This single centre prospective diagnostic study evaluates three RDT (NADAL(R), Panbio, MEDsan(R)) in comparison to quantitative reverse transcription polymerase chain reaction (RT-qPCR). 9,760 oropharyngeal screening samples regarding SARS-CoV-2 VOC and COVID-19 vaccination in paediatric hospitalised patients aged younger than 18 years were enrolled. Findings RDT sensitivity was 44{middle dot}7% (157/351, 95% CI 39{middle dot}6%-50{middle dot}0%) compared to the reference standard RT-qPCR, specificity 99{middle dot}8% (9,392/9,409, 95% CI 99{middle dot}7%-99{middle dot}9%). Most SARS-CoV-2 infections considered were caused by Omicron VOC. Diagnostic accuracy of RDT depended on specimen containing viral load with a decreasing RDT sensitivity by descending viral load, corresponding with a significantly impaired sensitivity in asymptomatic children. A sensitivity of 71{middle dot}0% was obtained for a viral load higher than 106 SARS-CoV-2 RNA copies per ml suggested as infectivity threshold. No significant differences in RDT sensitivity could be observed regarding gender, symptoms, COVID-19 vaccination status, and VOC. Interpretation In a paediatric population, RDT have proven to reliably detect potentially highly infectious patients with a viral load of at least 106 SARS-CoV-2 RNA copies per ml. Due to the low sensitivity in asymptomatic individuals, the usefulness of RDT seems limited in large scale SARS-CoV-2 screening programs. Funding Federal Ministry for Education and Science (BMBF), Free State of Bavaria

Bivalent BNT162b2mRNA original/Omicron BA.4-5 booster vaccination: adverse reactions and inability to work compared to the monovalent COVID-19 booster (preprint)

In the light of emerging SARS CoV 2 variants of concern (VOC), bivalent COVID 19 vaccines combining the wild-type spike mRNA with an Omicron VOC BA.1 or BA.4-5 spike mRNA became available. This non randomized controlled study examined adverse reactions, PRN (pro re nata) medication intake and inability to work after a fourth COVID-19 vaccination among 76 healthcare workers. As fourth dose either the original, monovalent BNT162b2mRNA (48.7%) or the bivalent BNT162b2mRNA original/Omicron BA.4-5 vaccine (51.3%) was administered. The rate of adverse reactions for the second booster dose was significantly higher among participants receiving the bivalent 84.6% (95% CI 70.3%-92.8%; 33/39) compared to the monovalent 51.4% (95% CI 35.9-66.6%; 19/37) vaccine (p=0.0028). Also, there was a trend towards an increased rate of inability to work and intake of PRN medication following bivalent vaccination. In view of preprints reporting inconclusive results in neutralizing antibody levels between the compared vaccines, our results and further studies on safety and reactogenicity of bivalent COVID-19 booster vaccines are highly important to aid clinical decision making in the choice between bivalent and monovalent vaccinations.

Immunogenicity and safety of coadministration of COVID-19 and influenza vaccination among healthcare workers (preprint)

Background A third dose of COVID-19 vaccination (COVID booster vaccination) has become established as an important measure to strengthen the immune response against SARS-CoV-2. In contrast, seasonal influenza vaccination has been an important infection prevention measure for years, especially among highly exposed healthcare workers (HCWs). Coadministration of vaccines against COVID-19 and seasonal influenza could be an efficient strategy to protect HCWs from two major viral respiratory infections. Yet, the immunogenicity and safety of coadministration remains to be evaluated. Methods This study examines the differences in Anti-SARS-CoV-2-Spike IgG antibody formation as well as side effects based on a digital questionnaire after a third COVID-19 vaccination with or without coadministration of a seasonal quadrivalent influenza vaccine (Influvac Tetra vaccine 2021/2022). 1,231 HCWs were recruited who received a mRNA-based booster COVID-19 vaccination (mRNA-1273 or BNT162b2mRNA) after basic immunisation with BNT162b2mRNA twice. Anti-SARS-CoV-2-Spike IgG levels were determined at least 14 days after vaccination by SERION ELISA agile SARS-CoV-2 IgG. Findings Anti-SARS-CoV-2-Spike IgG concentrations were by 25.4% lower in individuals with coadministration of the seasonal quadrivalent influenza vaccination than without (p<0.01). There was no statistically significant difference in the reported side effects. The concentration of Anti-SARS-CoV-2-Spike IgG was higher in HCWs who had received the influenza vaccine concomitantly with mRNA-1273 than with BNT162b2mRNA as third COVID-19 vaccine (p<0.0001). Interpretation Coadministration of the seasonal quadrivalent influenza vaccine significantly limits the levels in Anti-SARS-CoV-2-Spike IgG levels, with a more restricted elevation in case of a BNT162b2mRNA booster vaccination compared with mRNA-1273 vaccine. The reduced humoral immune response in case of coadministration needs to be considered in seasonal vaccination recommendations, although the consequences of lower Anti-SARS-CoV-2-Spike IgG levels for the protection against SARS-CoV-2 infection and severe COVID-19 disease course are currently unknown. An augmented mRNA-based COVID-19 vaccine dosage may compensate for the restricted immunogenicity in case of coadministration. Funding This study was funded by the Federal Ministry for Education and Science (BMBF) through a grant provided to the University Hospital of Wuerzburg by the Network University Medicine on COVID-19 (B-FAST, grant-No 01KX2021) as well as by the Free State of Bavaria with COVID-research funds provided to the University of Wuerzburg, Germany. Nils Petri is supported by the German Research Foundation (DFG) funded scholarship UNION CVD.

Influencing factors of Anti-SARS-CoV-2-Spike IgG antibody titres in healthcare workers - A cross-section study (preprint)

BackgroundAgainst the background of the current COVID-19 infection dynamics with the rapid spread of SARS-CoV-2 variants of concern (VOC), above all the Omicron VOC, the immunity of healthcare workers (HCWs) against SARS-CoV-2 continues to be of high importance. Vaccination plays a central role in reducing the severity and potentially the spread of the disease. In healthcare, this is important to prevent disease-related staff shortages. However, there is a lack of data on factors influencing the humoral immune response. AimThe aim of our study was to determine factors influencing the level of Anti-SARS-CoV-2-Spike IgG after SARS-CoV-2 infection or vaccination in healthcare workers. Methods1,750 study participants were recruited who met the following inclusion criteria: age [≥] 18 years, PCR-confirmed SARS-CoV-2 infection and/or at least one dose of COVID-19 vaccination, working in health care. Anti-SARS-CoV-2-Spike IgG titres were determined by SERION ELISA agile SARS-CoV-2 IgG. ResultsMean Anti-SARS-CoV-2-Spike IgG levels increased significantly with the number of COVID-19 vaccinations (92.2 BAU/ml for single dose, 140.9 BAU/ml for two doses and 1,144.3 BAU/ml after threefold vaccination). Hybrid COVID-19 immunized respondents (after infection and vaccination) had significantly higher antibody titres compared with participants after infection only (525.4 BAU/ml vs. 105.7 BAU/ml). Anti-SARS-CoV-2-Spike IgG titres declined significantly with time after administration of the second vaccine dose. Smoking and high age were associated with lower titres. ConclusionBoth recovered and vaccinated HCWs presented a predominantly good humoral immune response with decreasing antibody levels over the temporal course. Smoking and higher age limited the humoral SARS-CoV-2 immunity. This reduced immune response is an important aspect as people with these risk factors are recognized as people with an increased risk for a severe course of disease.

COVID-19 patients share common, corticosteroid-independent features of impaired host immunity to pathogenic molds (preprint)

Patients suffering from coronavirus disease-2019 (COVID-19) are at high risk for deadly secondary fungal infections such as COVID-19-associated pulmonary aspergillosis (CAPA) and COVID-19-associated mucormycosis (CAM). Despite this clinical observation, direct experimental evidence for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)-driven alterations of antifungal immunity is scarce. Using an ex-vivo whole blood (WB) stimulation assay, we challenged blood from twelve COVID 19 patients with Aspergillus fumigatus and Rhizopus arrhizus antigens and studied the expression of activation, maturation, and exhaustion markers, as well as cytokine secretion. Compared to healthy controls, T-helper cells from COVID-19 patients displayed increased expression levels of the exhaustion marker PD-1 and weakened A. fumigatus- and R. arrhizus-induced activation. While baseline secretion of proinflammatory cytokines was massively elevated, WB from COVID-19 patients elicited diminished release of T-cellular (e.g., IFN-{gamma}, IL-2) and innate immune cell-derived (e.g., CXCL9, CXCL10) cytokines in response to A. fumigatus and R. arrhizus antigens. Additionally, samples from COVID-19 patients showed deficient granulocyte activation by mold antigens and reduced fungal killing capacity of neutrophils. These features of weakened anti-mold immune responses were largely decoupled from COVID-19 severity, the time elapsed since diagnosis of COVID-19, and recent corticosteroid uptake, suggesting that impaired anti-mold defense is a common denominator of the underlying SARS-CoV-2 infection. Taken together, these results expand our understanding of the immune predisposition to post-viral mold infections and could inform future studies of immunotherapeutic strategies to prevent and treat fungal superinfections in COVID-19 patients.

Diagnostic accuracy and feasibility of a rapid SARS-CoV-2 antigen test in general practice – a prospective multicenter validation and implementation study (preprint)

Background PCR testing is considered the gold standard for SARS-CoV-2 diagnosis but its results are earliest available hours to days after testing. Rapid antigen tests represent a diagnostic tool enabling testing at the point of care. To date, most rapid antigen tests were validated by the manufacturer or in controlled laboratory settings only. External validation at the point of care, particularly in general practice where the test is frequently used, is needed. Furthermore, it is unclear how well point of care tests are accepted by the practice staff.Methods In this prospective multicenter validation study in primary care, general practitioners included adult individuals presenting with symptoms suggesting COVID-19. Each patient was tested first with a nasopharyngeal swab for the point of care test and then with a second swab for PCR testing. Using the RT-PCR result as a reference, we calculated specificity, sensitivity, positive predictive value and negative predictive value, with their 95% confidence intervals. General practitioners and medical assistants completed a survey to assess feasibility and usefulness of the point of care tests.Results In 40 practices in Würzburg, Germany, 1518 patients were recruited between 12/2020 and 06/2021. The point of care test achieved a sensitivity of 78.3% and a specificity of 99.5% compared to RT-PCR. With a prevalence of 9.5%, the positive predictive value was 93.9% and the negative predictive value was 97.8%. General practitioners rated the point of care test as a helpful tool to support diagnostics in patients with signs and symptoms suggestive for infection, particularly in situations where decision on further care is needed at short notice.Conclusion The point of care test used in this study showed a sensitivity below the manufacturer's specification (Sensitivity 96.25%) in the practice but high values for specificity and high positive predictive value and negative predictive value. Although widely accepted in the practice, measures for further patient management require a sensitive interpretation of the point of care test results.

Aspergillus Tracheobronchitis in COVID-19 ARDS Patients – A Cohort Study (preprint)

Background: Coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome patients are at risk for fungal infections, especially aspergillosis and mucormycosis. COVID-19-associated pulmonary aspergillosis (CAPA) is differentiated in a pulmonary form and Aspergillus tracheobronchitis (ATB). During the first wave of the pandemic, bronchoscopy for diagnosing Aspergillus superinfections was rarely performed in COVID-19 patients, so that detailed on data on ATB in CAPA patients is scarce. We analyzed prevalence and mortality of tracheobronchitis in patients with CAPA.Methods: We conducted a retrospective, single-centre study at the 14-bed intensive care unit (ICU) of the Department I of Internal Medicine of the University Hospital of Cologne, Germany from March 2020 to February 2021. CAPA patients were identified by twice weekly analysis of tracheal aspirates for Aspergillus growth, Aspergillus DNA (PCR) and galactomannan combined with serum galactomannan testing. In case of positive results, bronchoscopy with the examination of trachea and lower airways and bronchoalveolar lavage followed.Findings: A total of 69 COVID-19 patients were admitted to the ICU, with 17 patients developing probable CAPA. All CAPA patients received bronchoscopy resulting in a clinical diagnosis of tracheobronchitis in 8 patients with signs of tracheal lesions, pseudomembranes or vulnerable bloody trachea. Seven bronchoalveolar lavages revealed culture and eight PCR positivity for Aspergillus fumigatus. In 7 of 8 tracheobronchitis patients, bronchoalveolar lavage samples tested positive for galactomannan antigen optical density index of >0.5. The overall mortality of CAPA patients was 52.9% and the overall mortality of ATB patients was 75%.Interpretation: Our data indicate a substantial prevalence of tracheobronchitis in this single-center cohort of CAPA patients. To facilitate early diagnosis bronchoscopic tracheal examination is crucial as computed tomography lacks diagnostic accuracy to enable timely initiation of therapy.Funding Information: This work was in part supported by the German Registry of COVID-19 Autopsies (www.DeRegCOVID.ukaachen.de), funded by the Federal Ministry of Health (ZMVI1-2520COR201), and the project DEFEAT PANDEMICs, funded by the Federal Ministry of Education and Research (01KX2021).Declaration of Interests: PK reports grants or contracts from German Federal Ministry of Research and Education and the State of North Rhine-Westphalia; Consulting fees Ambu GmbH, Gilead Sciences, Noxxon N.V. and Pfizer Pharma; Honoraria for lectures from Akademie für Infektionsmedizin e.V., Ambu GmbH, Astellas Pharma, BioRad Laboratories Inc., European Confederation of Medical Mycology, Gilead Sciences, GPR Academy Ruesselsheim, medupdate GmbH, MedMedia, MSD Sharp & Dohme GmbH, Pfizer Pharma GmbH, Scilink Comunicación Científica SC and University Hospital and LMU Munich; Participation on an Advisory Board from Ambu GmbH, Gilead Sciences, Pfizer Pharma; A pending patent currently reviewed at the German Patent and Trade Mark Office; Other non-financial interests from Elsevier, Wiley and Taylor & Francis online outside the submitted work. SvS none. JGB reports scientific grants and travel expenses from Kite/Gilead outside the submitted work. FF has a clinician scientist position supported by the deans office, medical faculty, University of Cologne. JSG none. FP none. BB reports honoraria, travel expenses and advisory role from/for Astellas, Celgene, Johnson & Johnson, Kite/Gilead, MSD, Novartis, Pfizer, Takeda and financing of scientific research by Astellas, Celgene, Kite/Gilead, MSD and Takeda outside the submitted work. DAE received honoraria from Sanofi and TAKEDA outside the submitted work. ASV reports travel grants from Gilead Sciences outside the submitted work. OK reports payment or honoraria for lectures, presentations or speakers bureaus by Gilead and Pfizer and receipt of equipment, materials, drugs, medical writing, gifts or other services by Pfizer, MSD, Basilea, Gilead, Virotech and Wako Fujifilm outside the submitted work. PB none. MK reports payment or honoraria for lectures, presentations or speakers bureaus by Gilead, MSD and Pfizer outside the submitted work. OAC reports grants or contracts from Amplyx, Basilea, BMBF, Cidara, DZIF, EU-DG RTD (101037867), F2G, Gilead, Matinas, MedPace, MSD, Mundipharma, Octapharma, Pfizer, Scynexis; Consulting fees from Amplyx, Biocon, Biosys, Cidara, Da Volterra, Gilead, Matinas, MedPace, Menarini, Molecular Partners, MSG-ERC, Noxxon, Octapharma, PSI, Scynexis, Seres; Honoraria for lectures from Abbott, Al 344 Jazeera Pharmaceuticals, Astellas, Grupo Biotoscana/United Medical/Knight, Hikma, MedScape, MedUpdate, Merck/MSD, Mylan, Pfizer; Payment for expert testimony from Cidara; Participation on a Data Safety Monitoring Board or Advisory Board from Actelion, Allecra, Cidara, Entasis, IQVIA, Jannsen, MedPace, Paratek, PSI, Shionogi; A pending patent currently reviewed at the German Patent and Trade Mark Office; Other interests from DGHO, DGI, ECMM, ISHAM, MSG-ERC, Wiley outside the submitted work.Ethics Approval Statement: Patients with CAPA were included in the FungiScope® global registry for emerging invasive fungal infections (https://www.clinicaltrials.gov; National Clinical Trials identifier NCT01731353), which was approved by the local ethics committee of the University of Cologne, Cologne, Germany (identifier 05-102).

Clinical performance evaluation of SARS-CoV-2 rapid antigen testing in point of care usage in comparison to RT-qPCR (preprint)

Background Antigen rapid diagnostic tests (RDT) for SARS-CoV-2 are fast, broadly available, and inexpensive. Despite this, reliable clinical performance data is sparse. Methods In a prospective performance evaluation study, RDT from three manufacturers (NADAL, Panbio, MEDsan) were compared to quantitative reverse transcription polymerase chain reaction (RT-qPCR) in 5 068 oropharyngeal swabs for detection of SARS-CoV-2 in a hospital setting. Viral load was derived from standardized RT-qPCR Cycle threshold (Ct) values. The data collection period ranged from November 12, 2020 to February 28, 2021. Findings Overall, sensitivity of RDT compared to RT-qPCR was 42.57% (95% CI 33.38%-52.31%), and specificity 99.68% (95% CI 99.48%-99.80%). Sensitivity declined with decreasing viral load from 100% in samples with a deduced viral load of 10^8 SARS-CoV-2 RNA copies per ml to 8.82% in samples with a viral load lower than 104 SARS-CoV-2 RNA copies per ml. No significant differences in sensitivity or specificity could be observed between the three manufacturers, or between samples with and without spike protein variant B.1.1.7. The NPV in the study cohort was 98.84%; the PPV in persons with typical COVID-19 symptoms was 97.37%, and 28.57% in persons without or with atypical symptoms. Interpretation RDT are a reliable method to diagnose SARS-CoV-2 infection in persons with high viral load. RDT are a valuable addition to RT-qPCR testing, as they reliably detect infectious persons with high viral loads before RT-qPCR results are available. Funding German Federal Ministry for Education and Science (BMBF), Free State of Bavaria

Performance of three SARS-CoV-2 immunoassays, three rapid lateral flow tests and a novel bead-based affinity surrogate test for the detection of SARS-CoV-2 antibodies in human serum (preprint)

For the control of immunity in COVID-19 survivors and vaccinated subjects there is an urgent need for reliable and rapid serological assays. Based on samples from 63 COVID-19 survivors up to seven months after symptom onset, and on 50 serum samples taken before the beginning of the pandemic, we compared the performance of three commercial immunoassays for the detection of SARS-CoV-2 IgA and IgG antibodies (Euroimmun SARS-COV-2 IgA/IgG, Mikrogen recomWell SARS-CoV-2 IgA/IgG, and SERION ELISA agile SARS-CoV-2 IgA/IgG) and three rapid lateral flow (immunochromatographic) tests (Abbott Panbio COVID-19 IgG/IgM, NADAL COVID-19 IgG/IgM, and Cleartest Corona 2019-nCOV IgG/IgM) with a plaque-reduction neutralization test (PRNT50) representing the gold standard. In addition, we report and validate a novel, non-commercial flow cytometry bead-based surrogate test. 57 out of 63 PCR-confirmed COVID-19 patients (90 %) showed neutralizing antibodies. The sensitivity of the seven assays ranged from 7.0 % to 98.3 %, the specificity from 86.0 % to 100.00 %. Only one commercial immunoassay showed a sensitivity and specificity of greater than 98 %. These data indicate abundant interassay variability.