Abstract Numerous nosocomial infections were observed in hospitals and other healthcare facilities during the COVID-19 pandemic, largely attributed to asymptomatic or pre-symptomatic carriers. SARS-CoV-2 screening data at admission of all hospitalised patients and accompanying persons of a tertiary-care hospital in Germany was included from 1 April 2020 to 31 December 2021. The first oropharyngeal swab of each newly admitted individual was tested for SARS-CoV-2 RNA using reverse transcription polymerase chain reaction (RT-qPCR). The overall testing costs and the costs per positively tested individual were analysed. Out of 111,271 screened individuals, 705 (0.6%) tested positive for SARS-CoV-2 by RT-qPCR. Among these, 236 cases (0.2%) had not been previously diagnosed and were identified through RT-qPCR admission screening. Of the newly detected cases,110 (0.1%) were asymptomatic without any known positive contact history. The specificity of RT-qPCR in screening use was 99.997% (95% CI 99.992–99.999%). The mean testing costs of identifying one SARS-CoV-2-positive individual through admission screening was €8,082.87. Long-term universal RT-qPCR admission screening detected a substantial number of otherwise unidentified SARS-CoV-2-positive individuals, proving its value as a infection control tool with an excellent specificity in screening use during the COVID-19 pandemic. This strategy represents an important lesson learned from the pandemic and may serve as a valuable infection control tool for future pandemics or seasonal pathogen surges.

Abstract Background Following the easing of preventive, non-pharmaceutical COVID-19 interventions (NPIs) during the late phase of the pandemic, acute respiratory infections (ARI) in children reemerged. We investigated the viral etiology, seasonality and clinical characteristics of children with ARI treated in primary care practices during this period. Methods We conducted a prospective, observational study on children ≤ 14 years of age, presenting with acute upper (URTI) or lower (LRTI) ARI in five pediatric primary care practices in Wuerzburg, Germany, from 10/2021 to 05/2022. A maximum of eight children per practice were included on one predefined day per week. Oropharyngeal swabs were analyzed using (multiplex) PCR for 18 viral pathogens. Results A total of 521 children (median age 3.3 years; IQR 1.6–5.5; 52% male) with ARI were enrolled (28% LRTI). At least one virus was detected in 85%, with human rhinovirus (HRV) (30%), Respiratory Syncytial Virus (RSV) (22%), and SARS-CoV-2 (16%) being the most frequent viruses. Co-detection (≥ 2 viruses) occurred in 156 (30%) patients, were most frequent in children < 2 years of age (38% of 164), and their rate decreased with increasing age (p = 0.012). Bocavirus (88% of 56), adenovirus (80% of 48) and endemic coronaviruses (70% of 42) showed the highest proportion of co-detection. RSV and human metapneumovirus (hMPV) were predominant in LRTI, whereas HRV and SARS-CoV-2 were more prevalent in URTI. The LRTI rate was 32% of 288 mono-detections and 23% of 156 co-detection. Conclusions During fall/winter 2021/2022, viral co-detection were common, possibly as a consequence of easing COVID-19-related NPIs, but were not associated with more severe clinical characteristics.

As part of the Wurzburg KiTa-CoV study series, SARS-CoV-2 pandemic-related attitudes/concerns of parents of preschool children attending day care centres were surveyed over a 21-month period. We expected associations between these parental attitudes/concerns and their change over the course of the pandemic, on the one hand, and the SARS-CoV-2 infection status of the children, on the other. Parents of children from nine day- care centres who completed a survey on pandemic-related attitudes/concerns in October 2020, July 2021 and July 2022, were included in the analysis. In July 2022, the children's infection status was determined by measuring nucleocapsid protein antibodies (N-AK) and, in the case of N-AK negative, unvaccinated children, the measurement results of spike protein antibodies (S-AK) against SARS-CoV-2 as indicators of previous infection were also taken into account. Changes in parental attitudes/concerns were analysed using trend tests, and their significance in predicting the child's infection status was analysed using multiple binomial regression analyses. Data were available from parents of 159 children (mean age 3.2 years). The overall group of parents showed an increasingly relaxed attitude towards the pandemic over the study period, although the parents' concerns towards a possible infection of their own increased. The infection status of the children could not be predicted from the initial attitudes and concerns of the parents. However, the subgroup of parents with an uninfected child tended to have a higher level of concerns over the course of the pandemic than the parents with an infected child and did not show the same increasing composure towards the pandemic event. The parents' increasing composure is understandable in the context of the reduced virulence of the virus variants prevailing over time, the increasing availability of testing strategies and vaccinations, and the withdrawal of pandemic-related restrictions. In addition, the mildness of most children's infections may have contributed to their parents' sense of security. The seemingly contradictory increase in parental concerns about infection may be related to the strong increase in the incidence due to omicron variant infections in the population since January 2022. It is possible that the higher level of concerns among parents of uninfected children had a protective effect behaviourally.

Allogeneic hematopoietic stem cell transplant (alloSCT) recipients frequently experience late-onset human cytomegalovirus (HCMV) reactivations following termination of letermovir prophylaxis. Letermovir prophylaxis extends the window for protective B- and T-cell reconstitution; however, our understanding of humoral responses and their contribution to HCMV immune control remains limited. Combining serological and flow cytometric analyses in 42 HCMV-seropositive alloSCT recipients, we herein provide the first comprehensive longitudinal (days 90-270 post-transplant) characterization of HCMV-specific humoral responses, natural killer (NK)-cell phenotypes, and γδ T cells in the letermovir era. HCMV controllers showed predominantly HCMV-specific IgG-driven responses, higher pre-reactivation Vδ1+ γδ T-cell frequencies, and stronger expansion of “memory-like” NK cells than patients with clinically significant CMV infection (csCMVi). In contrast, csCMVi patients showed delayed HCMV-specific IgG production, IgM-skewed responses, and stronger postreactivation expansion of memory B cells and Vδ1+ γδ T cells. Early (day 90) γδ T-cell reconstitution was associated with subsequent HCMV control. HCMV-specific IgG levels correlated only weakly with γδ T cells but showed distinct associations with “memory-like” NK-cell reconstitution in HCMV controllers, suggesting synergisms between humoral and cellular immunity. Collectively, these findings highlight a need to study anti-HCMV immune protection beyond type-1 T cells and refine risk stratification models in alloSCT patients by inclusion of novel immune markers such as γδ T-cell frequencies and phenotypes. Leveraging the extended B-cell reconstitution window created by letermovir, novel immunotherapies (e.g., therapeutic antibodies) and future vaccines might boost humoral anti-HCMV immunity and benefit from synergisms with γδ T cells and “memory-like” NK cells in improving HCMV control.

OBJECTIVES:Worldwide, data on the burden of pediatric, outpatient-treated lower respiratory tract infections (LRTI) are limited. We investigated their viral etiology, clinical characteristics and family impact in Würzburg/Germany. METHODS:Children aged <2 years presenting with febrile LRTI at nine pediatric practices from 11/2022-10/2023 were recorded. In a subset, oropharyngeal swabs were tested with multiplex-PCR for 18 respiratory viruses; clinical data were physician-reported and parent-reported (14-days diary; 1/3/12-month follow-up). RESULTS:Among 474 recorded children, diagnoses were obstructive bronchitis/bronchiolitis (93.2%), pneumonia (3.4%), and stenosing laryngotracheitis (6.5%). Oropharyngeal swabs were collected from 107/474 (22.6%); RSV (33.6%), rhinovirus (27.1%), and hMPV (15.0%) were most frequently detected. Pediatricians classified 49.5%/48.6%/1.9% (of 107) as mildly/moderately/severely ill; 72.0% received beta-sympathomimetics; 15.0% antibiotics. In 65 diary-documented children, illness lasted 18 days (median; IQR 14-34), 46.2%/3.1% required additional visits/hospitalization, and parents reported 2.5 workdays missed (median). After 1/3/12 months, recurrent LRTI occurred in 11.3%/18.8%/35.5% and wheezing in 14.1%/20.2%/32.2%, with wheezing at 3- or 12-month follow-up associated with recurrent LRTI (Odds Ratio 13 and 7, P < 0.01). CONCLUSIONS:Outpatient-treated LRTI in infants were usually mild/moderate but resolved slowly, with substantial family impact. RSV, rhinovirus, and hMPV predominated. Wheezing was reported in one-third after 12 months and was associated with recurrent LRTI. The present results provide a basis for assessing the impact of the recently recommended RSV immunization for all infants in Germany on the substantial burden of outpatient-treated LRTI in this particularly vulnerable age group.

This study investigated changes in the incidence and age distribution of RSV-associated lower respiratory tract infections (RSV-LRTI) among children in Northern Bavaria after the general recommendation of Nirsevimab immunization in 2024. Postnatal Nirsevimab immunization coverage was assessed at the University Hospital Würzburg (UKW) in children born between 11/2024 and 03/2025. Age distribution of in- and outpatients < 2 years with PCR-confirmed RSV-LRTI was assessed from UKW (ICD-10 based) and pediatric practices in Würzburg for November-March in 2022/23 (S1), 2023/24 (S2) and 2024/25 (S3). Age distribution of RSV cases from nationwide mandatory laboratory RSV surveillance (Robert Koch-Institute) was analyzed for November-March in 2023/24 and 2024/25. Between 11/2024 and 03/2025, postnatal Nirsevimab immunization coverage for newborns at the UKW was 68

Allogeneic hematopoietic stem cell transplant (alloSCT) recipients often experience late-onset human cytomegalovirus (HCMV) reactivations following termination of letermovir prophylaxis. Letermovir prophylaxis extends the window for protective B- and T-cell reconstitution; however, our understanding of humoral responses and their contribution to HCMV immune control remains limited. Combining serological and flow cytometric analyses in 42 HCMV-seropositive alloSCT recipients, we herein provide the first comprehensive longitudinal (days 90-270 post-transplant) characterization of HCMV-specific humoral responses, natural killer (NK)-cell phenotypes, and γδ T cells in the letermovir era. HCMV controllers showed predominantly IgG-driven responses, higher pre-reactivation Vδ1+ T-cell frequencies, and stronger expansion of ″memory-like″ NK cells than patients with clinically significant CMV infection (csCMVi). In contrast, csCMVi patients showed delayed HCMV-specific IgG production, IgM-skewed humoral responses, and stronger post-reactivation expansion of memory B cells and Vδ1+ γδ T cells. Early γδ T-cell reconstitution by day 90 was predictive of future HCMV control. HCMV-specific IgG levels correlated only weakly with γδ T cells but showed distinct associations with ″memory-like″ NK-cell reconstitution in HCMV controllers, suggesting synergisms between humoral and cellular immunity. Collectively, these findings highlight a need to study anti-HCMV immune protection beyond type-1 T cells and refine risk stratification models in alloSCT patients by inclusion of novel immune markers such as γδ T-cell frequencies and phenotypes. Leveraging the extended B-cell reconstitution window created by letermovir, novel immunotherapies (e.g., therapeutic antibodies) and future vaccines might boost humoral anti-HCMV immunity and benefit from synergisms with γδ T cells and ″memory-like″ NK cells in improving HCMV control. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was funded by a grant from the German Research Council (DFG) within the DFG Research Unit FOR 2830 (KR 5761/1-2, project number 398367752 (to S.K.); EI 269/10-2, project number 398367752 (to H.E.); DO 1275/7-2 (to L.D.); HE2526/9-2 (to H.H.)). S.K. was further supported by a fellowship of the Interdisciplinary Center for Clinical Research (IZKF) and the trust Forschung Hilft. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the Ethics Committees of the University of Wuerzburg, Germany (protocol code 17/19-sc). Written informed consent was obtained from all patients. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The datasets generated and analysed in this study are available from the corresponding author upon reasonable request.

Im Rahmen der Würzburger KiTa-CoV-Studienserie wurden pandemiebezogene Einstellungen/Sorgen der Eltern von in Tagesstätten betreuten Vorschulkindern über einen 21-monatigen Zeitraum erhoben. Wir erwarteten Zusammenhänge zwischen diesen elterlichen Einstellungen/Sorgen und deren Veränderung im Pandemieverlauf einerseits und dem SARS-CoV-2-Infektionsstatus der Kinder andererseits. Eltern von Kindern aus 9 KiTas, die im Oktober 2020, Juli 2021 und Juli 2022 an einer Befragung zu ihren pandemiebezogenen Einstellungen/Sorgen teilgenommen hatten, wurden in die Analyse eingeschlossen. Im Juli 2022 wurde der SARS-CoV-2 Infektionsstatus der Kinder mittels Messung von Nukleokapsid-Protein-Antikörpern (N-AK) bestimmt und bei N-AK-negativen, ungeimpften Kindern zusätzlich das Messergebnis von Spike-Protein-Antikörpern (S-AK) berücksichtigt. Veränderungen der elterlichen Einstellungen/Sorgen wurden über Trendtests analysiert, deren Bedeutung zur Prädiktion des Infektionsstatus des Kindes über multiple binomiale Regressionsanalysen. Angaben lagen zu Eltern von 159 Kindern (Altersdurchschnitt 3,2 Jahre) vor. Insgesamt zeigten die Eltern eine über den Untersuchungszeitraum zunehmend gelassene Einstellung gegenüber dem Pandemiegeschehen; die Sorgen der Eltern bezüglich einer möglichen eigenen Infektion nahmen jedoch zu. Über die initialen Einstellungen/Sorgen der Eltern konnte der Infektionsstatus der Kinder nicht vorhergesagt werden. Die Untergruppe der Eltern mit einem nicht infizierten Kind wies aber im Verlauf der Pandemie ein tendenziell höheres Sorgenniveau auf als Eltern mit einem infizierten Kind und zeigte nicht wie diese eine zunehmende Gelassenheit gegenüber dem Pandemiegeschehen. Eine zunehmende Gelassenheit der Eltern ist nachvollziehbar vor dem Hintergrund der im Zeitverlauf verminderten Virulenz der vorherrschenden Virusvarianten, der zunehmenden Verfügbarkeit von Teststrategien und Impfungen sowie der Rücknahme pandemiebezogener Einschränkungen. Zusätzlich dürften die zumeist milden Infektionen der Kinder zum Sicherheitsempfinden beigetragen haben. Die im scheinbaren Widerspruch dazu ansteigenden Sorgen der Eltern vor einer eigenen Infektion könnten mit der starken Zunahme der Inzidenz in der Bevölkerung ab Januar 2022 aufgrund der hochansteckenden Omikron-Variante in Zusammenhang stehen. Möglicherweise hatte das höhere Sorgenniveau der Eltern nicht infizierter Kinder verhaltensbezogen einen protektiven Effekt. As part of the Würzburg KiTa-CoV study series, SARS-CoV-2 pandemic-related attitudes/concerns of parents of preschool children attending day care centres were surveyed over a 21-month period. We expected associations between these parental attitudes/concerns and their change over the course of the pandemic on the one hand and the SARS-CoV-2 infection status of the children on the other. Parents of children from nine day-care centres who completed a survey on pandemic-related attitudes/concerns in October 2020, July 2021 and July 2022, were included in the analysis. In July 2022, the children's infection status was determined by measuring nucleocapsid protein antibodies (N-AK) and, in the case of N-AK negative, unvaccinated children, the measurement results of spike protein antibodies (S-AK) against SARS-CoV-2 as indicators of previous infection were also taken into account. Changes in parental attitudes/concerns were analysed using trend tests, and their significance in predicting the child's infection status was analysed using multiple binomial regression analyses. Data were available from parents of 159 children (mean age 3.2 years). The overall group of parents showed an increasingly relaxed attitude towards the pandemic over the study period, although the parents' concerns towards a possible infection of their own increased. The infection status of the children could not be predicted from the initial attitudes and concerns of the parents. However, the subgroup of parents with an uninfected child tended to have a higher level of concerns over the course of the pandemic than the parents with an infected child and did not show the same increasing composure towards the pandemic event. The parents' increasing composure is understandable in the context of the reduced virulence of the virus variants prevailing over time, the increasing availability of testing strategies and vaccinations, and the withdrawal of pandemic-related restrictions. In addition, the mildness of most children's infections may have contributed to their parents' sense of security. The seemingly contradictory increase in parental concerns about infection may be related to the strong increase in the incidence due to omicron variant infections in the population since January 2022. It is possible that the higher level of concerns among parents of uninfected children had a protective effect behaviourally.

ABSTRACTIntroductionDuring 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®, Panbio™, MEDsan®) 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.

BACKGROUND:Due to their clinical training and secondary activities in the hospital, medical students are exposed to contact with SARS-CoV-2 infected people more often than the general population. We determined the seroprevalence of SARS-CoV-2 antibodies in medical students in clinical training at different times during the pandemic and asked participants about possible SARS-CoV-2 exposures in both medical and private settings. METHODS:From May 2020 to June 2021, medical students each in their 3rd year of training at the University Hospital Würzburg participated in the cross-sectional survey. All SARS-CoV-2 unvaccinated students were offered a determination of their SARS-CoV-2 serostatus. The blood samples were tested by an immunoassay (Elecsys, Roche) for IgG/IgM/IgA antibodies against the SARS-CoV-2 N antigen. Demographic data, SARS-CoV-2 disease and vaccination status, as well as possible SARS-CoV-2 exposures were collected using a questionnaire. RESULTS:Overall, 383 (86.1%) of 445 students took part in the cross-sectional survey (65% female; median age 22 years; IQR 21-24). Serostatus was determined in 223 (58.2% of 383) SARS-CoV-2 unvaccinated participants. In the period between the beginning of the pandemic in Germany (February 2020) and the time of the survey, 332 (86.7% of 383) students stated that they worked in the medical field, mainly in the context of clinical traineeships (76.8%) or secondary activities with patient contact (48.8%); 129 (33.7%) reported previous contact with a COVID-19 patient, of which 78.3% of contacts took place at a medical facility. Antibodies against SARS-CoV-2 were detected in 8 (3.6%) of the 223 unvaccinated participants tested, and in 3 infected persons an association between infection and contact in the course of medical activity seemed likely. CONCLUSION:Despite frequent patient contact and the associated increased risk of infection, medical students in their 3rd year of training did not show an increased seroprevalence compared to the general population and showed a lower or similar seroprevalence rate than medical students in other European countries in the first 18 months of the pandemic. This indicates sufficient protection of medical students at the beginning of clinical training through the hygiene and infection protection measures implemented at that time during medical activities.

Background SARS-CoV-2 antigen rapid detection tests (RDTs) emerged as point-of-care diagnostics alongside reverse transcription polymerase chain reaction (RT-qPCR) as reference. Methods In a prospective performance assessment from 12 November 2020 to 30 June 2023 at a single centre tertiary care hospital, the sensitivity and specificity fi city (primary endpoints) of RDTs from three manufacturers (NADAL (R), (R) , PanbioTM, TM , MEDsan (R)) (R) ) were compared to RT-qPCR as reference standard among patients, accompanying persons and staff aged >= six month in large-scale, clinical screening use. Regression models were used to assess influencing fl uencing factors on RDT performance (secondary endpoints). Findings Among 78,798 paired RDT/RT-qPCR results analysed, overall RDT sensitivity was 34.5% (695/2016; 95% CI 32.4-36.6%), - 36.6%), specificity fi city 99.6% (76,503/76,782; 95% CI 99.6-99.7%). - 99.7%). Over the pandemic course, sensitivity decreased in line with a lower rate of individuals showing typical COVID-19 symptoms. The lasso regression model showed that a higher viral load and typical COVID-19 symptoms were directly significantly fi cantly correlated with the likelihood of a positive RDT result in SARS-CoV-2 infection, whereas age, sex, vaccination status, and the Omicron VOC were not. Interpretation The decline in RDT sensitivity throughout the pandemic can primarily be attributed to the reduced prevalence of symptomatic infections among vaccinated individuals and individuals infected with Omicron VOC. RDTs remain valuable for detecting SARS-CoV-2 in symptomatic individuals and offer potential for detecting other respiratory pathogens in the post-pandemic era, underscoring their importance in infection control efforts. Copyright (c) 2024 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Zusammenfassung Hintergrund Medizinstudierende sind bedingt durch ihre klinische Ausbildung und bei Nebentätigkeiten in der Klinik häufiger Kontakten zu SARS-CoV-2-Infizierten ausgesetzt als die Allgemeinbevölkerung. Wir bestimmten die Seroprävalenz von SARS-CoV-2-Antikörpern bei Medizinstudierenden in der klinischen Ausbildung zu verschiedenen Zeitpunkten in der Anfangsphase der Pandemie und befragten die Teilnehmenden zu möglichen SARS-CoV-2-Expositionen im medizinischen und im privaten Bereich. Methodik Im Zeitraum Mai 2020 bis Juni 2021 wurden Medizinstudierende des jeweiligen 3. Studienjahres (6. Fachsemester) am Universitätsklinikum Würzburg befragt und SARS-CoV-2-Ungeimpften eine Bestimmung ihres SARS-CoV-2-Serostatus angeboten. Die Blutproben wurden mittels Immunoassay (Elecsys, Roche) auf IgG/IgM/IgA-Antikörper gegen das SARS-CoV-2 N-Antigen getestet. Demographische Daten, SARS-CoV-2-Erkrankungs- und Impfstatus, sowie mögliche SARS-CoV-2 Expositionen wurden mithilfe eines Fragebogens erfasst. Ergebnisse 383 (86,1%) von 445 Studierenden beteiligten sich an der Querschnittsbefragung (65% weiblich; Altersmedian 22 Jahre; IQR 21–24). Von 223 (58,2% von 383) ungeimpften Teilnehmenden wurde der Serostatus ermittelt. Im Zeitraum zwischen Pandemiebeginn in Deutschland (Februar 2020) und dem Befragungszeitpunkt gaben 332 (86,7% von 383) an, eine Tätigkeit im medizinischen Bereich auszuüben, vor allem im Rahmen von Famulaturen (76,8%) oder Nebentätigkeiten mit Patientenkontakt (48,8%). 129 (33,7%) gaben einen vorangegangenen Kontakt zu einem COVID-19-Patienten an, davon fanden 78,3% der Kontakte in einer medizinischen Einrichtung statt. Bei 8 (3,6%) der 223 getesteten, ungeimpften Teilnehmenden konnten Antikörper gegen SARS-CoV-2 nachgewiesen werden, dabei ließ sich bei 3 Infizierten ein Zusammenhang zwischen der Infektion und einem Kontakt im Rahmen der medizinischen Tätigkeit vermuten. Schlussfolgerung Trotz häufigen Patientenkontaktes und des damit möglicherweise einhergehenden erhöhten Infektionsrisikos zeigten Medizinstudierende des 3. Studienjahres in den ersten 18 Monaten der Pandemie gegenüber der Allgemeinbevölkerung keine erhöhte Seroprävalenz und eine niedrigere bzw. ähnliche Seroprävalenzrate wie Medizinstudierende in anderen europäischen Ländern. Dies weist auf einen ausreichenden Schutz von Medizinstudierenden zu Beginn ihrer klinischen Ausbildung durch die damaligen Hygiene- und Infektionsschutzmaßnahmen bei medizinischen Tätigkeiten hin.

Objectives: Antigen rapid diagnostic tests (RDTs) for SARS coronavirus 2 (SARS-CoV-2) are quick, widely available, and inexpensive. Consequently, RDTs have been established as an alternative and additional diagnostic strategy to quantitative reverse transcription polymerase chain reaction (RT-qPCR). However, reliable clinical and large-scale performance data specific to a SARS-CoV-2 virus variant of concern (VOC) are limited, especially for the Omicron VOC. The aim of this study was to compare RDT performance among different VOCs. Methods: This single-centre prospective performance assessment compared RDTs from three manufacturers (NADAL, Panbio, MEDsan) with RT-qPCR including deduced standardized viral load from oropharyngeal swabs for detection of SARS-CoV-2 in a clinical point-of-care setting from November 2020 to January 2022.

•SARS-CoV-2 rapid antigen detection tests (RDT) were evaluated among children.•9760 oropharyngeal samples in paediatric patients were enrolled.•RDT sensitivity was 44.7% compared to RT-qPCR.•SARS-CoV-2 virus variant of concern and COVID-19 vaccination status did not have a significant impact of RDT sensitivity.

Background: Antigen rapid diagnostic tests (RDT) for SARS-CoV-2 are quick, widely available, and inexpensive. Consequently, RDT have been established as an alternative and additional diagnostic strategy to quantitative reverse transcription polymerase chain reaction (RT-qPCR). However, reliable SARS-CoV-2 virus variant of concern (VOC) specific clinical and large-scale performance data is limited, especially for Omicron VOC.Methods: This single-centre prospective performance assessment compares RDT from three manufacturers (NADAL®, Panbio™, MEDsan®) with RT-qPCR including deduced standardised viral load from 35,479 oropharyngeal swabs for detection of SARS-CoV-2 in a clinical point-of-care setting.Findings: RDT sensitivity compared to RT-qPCR was 38·50% (95% CI 34·00%–43·20%) with an overall specificity of 99·67% (95% CI 99·60%–99·72%). RDT sensitivity depended clearly on viral load with decreasing sensitivity accompanied by descending viral load. VOC dependent sensitivity assessment showed 42·86% (95% CI 32·82%–53·52%) for wild-type SARS-CoV-2 , 43·42% (95% CI 32·86%–54·61%) for Alpha VOC, 37·67% (95% CI 30·22%–45·75%) for Delta VOC, and 33·67% (95% CI 25·09%–43·49%) for Omicron VOC. Sensitivity in samples with high viral loads was significantly lower in Omicron VOC (50·00%, 95% CI 36·12%–63·88%) compared to wild-type virus (79·31%, 95% CI 61·61%–90·15%, p=0·015).Interpretation: RDT sensitivity for detection of the Omicron VOC is reduced in infectious individuals with high viral load, which curtails the effectiveness of RDT. This aspect further limits RDT use although RDT are still an irreplaceable diagnostic tool for rapid, economic, point-of-care and extensive SARS-CoV-2 screening use.Funding: Federal Ministry for Education and Science (BMBF), Free State of Bavaria. Declaration of Interest: None of the authors has any conflict of interest.Ethical Approval: The Ethics committee of the University of Wuerzburg considered the study protocol and waived the need to formally apply for ethical clearance due to the study design (File N 20210813 01).

Respiratory viruses were detected by multiplex-polymerase chain reaction from oropharyngeal swabs in 114/168 (67.9%) children with acute respiratory infection presenting to 5 pediatric practices in Germany between November 2020 and April 2021. In contrast to rhino- (48.8%), adeno- (14.3%) and endemic coronaviruses (14.9%), SARS-CoV-2 and influenza virus were detected only once; respiratory syncytial virus was not detected. This demonstrates differing impacts of pandemic infection control measures on the spread of respiratory viruses.