Background: Antigen rapid diagnostic tests (RDT) for SARS-CoV-2 are fast, broadly available, and inexpensive. Despite this, reliable clinical performance data from large field studies is sparse. Methods: In a prospective performance evaluation study, RDT from three manufacturers (NADAL®, Panbio™, MEDsan®, conducted on different samples) 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 standardised RT-qPCR Cycle threshold (C t ) values. The data collection period ranged from November 12, 2020 to February 28, 2021. Findings: The sensitivity of RDT compared to RT-qPCR was 42·57% (95% CI 33·38%–52·31%). The specificity was 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 10 4 SARS-CoV-2 RNA copies per ml. No significant differences in sensitivity or specificity could be observed 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.

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Seasonal influenza vaccination is established as important infection prevention measure, especially among highly exposed healthcare workers (HCWs) [1]. Coadministration with the third dose of COVID-19 vaccine could be an efficient strategy protecting HCWs from two major viral respiratory infections [2][3][4]. To date, the humoral immunogenicity and side-effects of a coadministered third COVID-19 and a seasonal quadrivalent influenza vaccine are still unclear, and the available data is limited in transferability to the general public [5][6][7]. This preference-based non-randomised controlled study examines the antibody-mediated immunogenicity and vaccine-related side-effects of mRNA-based COVID-19 and seasonal influenza vaccine coadministration in HCWs.1231 participants of the CoVacSer study with two doses of BNT162b2mRNA (30 µg mRNA each) as basic COVID-19 immunisation received a third dose of mRNA-based COVID-19 vaccine administering BNT162b2mRNA (30 µg mRNA) or mRNA-1273 (50 µg mRNA) depending on age and vaccine availability. HCWs could opt for a simultaneous influenza vaccine coadministration (Influvac Tetra vaccine 2021/2022) injected intramuscularly into the opposite arm. HCWs without coadministration received either no seasonal influenza vaccination or at least 14 days apart from the COVID-19 booster. Convalescent HCWs having passed a PCR-confirmed SARS-CoV-2 infection were excluded.Pseudonymised serum blood samples combined with a questionnaire were collected from 1 October 2021 to 31 January 2022 between 14 and 90 days after the COVID-19 vaccination. Anti-SARS-CoV-2-spike IgG levels were obtained using the SERION ELISA agile SARS-CoV-2 IgG (SERION diagnostics, Wuerzburg, Germany) [8].The statistical analyses were performed with R (version 3.1.2) on logarithmised anti-SARS-CoV-2-spike IgG concentrations based on a multiple linear regression analysis. The parameters including potential influencing factors were estimated using a generalised least squares fit (R package nlme) [9,10]. Statistical subgroup differences of the independent categorical variables were calculated with the estimated marginal means. Using the Tukey test statistics, pairwise post hoc tests were performed to expose statistically significant differences. The emmeans package was used to estimate marginal means and to calculate pairwise differences [11]. Investigating the role of side-effects, pairwise Fisher exact tests were performed. To correct against multiple testing, p-values were adjusted using the Benjamini-Yekutielie procedure [12]. Only adjusted p-values below a significance level of 0.05 were considered statistically significant.The study protocol was approved by the ethics committee of the University of Wuerzburg in accordance with the Declaration of Helsinki (file number 79/21). 20.2% (249/1231) of all participants opted for coadministration, whereas 90.4% (225/249) received BNT162b2mRNA and 9.6% (24/249) mRNA-1273 as COVID-19 booster vaccine. 79.8% (982/1231) of all participants were vaccinated with a mRNA-based COVID-19 vacci...

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Against the background of the current COVID‐19 infection dynamics with its rapid spread of SARS‐CoV‐2 variants of concern (VOC), the immunity and the vaccine prevention of healthcare workers (HCWs) against SARS‐CoV‐2 continues to be of high importance. This observational cross‐section study assesses factors influencing the level of anti‐SARS‐CoV‐2‐spike IgG after SARS‐CoV‐2 infection or vaccination. One thousand seven hundred and fifty HCWs were recruited meeting the following inclusion criteria: age ≥18 years, PCR‐confirmed SARS‐CoV‐2 infection convalescence and/or at least one dose of COVID‐19 vaccination. anti‐SARS‐CoV‐2‐spike IgG titers were determined by SERION ELISA agile SARS‐CoV‐2 IgG. Mean anti‐SARS‐CoV‐2‐spike IgG levels increased significantly by number of COVID‐19 vaccinations (92.2 BAU/ml for single, 140.9 BAU/ml for twice and 1144.3 BAU/ml for threefold vaccination). Hybrid COVID‐19 immunized respondents (after infection and vaccination) had significantly higher antibody titers compared with convalescent only HCWs. Anti‐SARS‐CoV‐2‐spike IgG titers declined significantly with time after the second vaccination. Smoking and high age were associated with lower titers. Both recovered and vaccinated HCWs presented a predominantly good humoral immune response. Smoking and higher age limited the humoral SARS‐CoV‐2 immunity, adding to the risk of severe infections within this already health impaired collective.

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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.

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