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Bone Biopsy (BB) with histomorphometric analysis still represents the gold standard for the diagnosis and classification of different forms of renal osteodystrophy. Bone biopsy is the only technique able to provide comprehensive information on all bone parameters, measuring static and dynamic parameters of turnover, cortical and trabecular microarchitecture, and mineralization defects. In nephrological practice, bone biopsy yields relevant indications to support therapeutic choices in CKD, heavily impacting the management and prognosis of uremic patients. Unfortunately, the use of bone biopsy has decreased; a lack of expertise in performing and interpreting, perceived procedure invasiveness and pain, and reimbursement issues have all contributed to this decline. Nevertheless, both bone biomarkers and instrumental images cannot be considered reliable surrogates for histological findings, being insufficiently accurate to properly evaluate underlying mineral and bone disorders. This is a multidisciplinary position paper from the Nephrology and Osteoporosis Italian Scientific Societies with the purpose of restating the role of bone biopsy in CKD patient management and of providing strong solutions to allow diffusion of this technique in Italy, but potentially also in other countries. The Italian approach through the optimization and standardization of bone biopsy procedure, the construction of the Italian Hub and Spoke network, and a request for adjustment and national homogenization of reimbursement to the Italian Health Ministry has led the way to implement bone biopsy and to improve CKD patient management and prognosis.

We present here a critical literature review and meta-analysis on the accuracy of the LumiraDX SARS-CoV-2 Antigen Test for diagnosing acute SARS-CoV-2 infection. An electronic search was conducted in the Scopus and Medline databases using the keywords "LumiraDX" AND "COVID-19" OR "SARS-CoV-2", without date (i.e., up to 1 February 2022) or language restrictions, for detecting clinical studies where the diagnostic accuracy of the LumiraDX SARS-CoV-2 Antigen Test was compared with reference molecular diagnostic methods. All studies where the rates of true positive, true negative, false positive and false negative cases were available for constructing a 2 × 2 table and providing pooled estimates of diagnostic sensitivity, specificity and accuracy were included in a pooled analysis. The study was conducted in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) reporting checklist. Eleven studies ( n = 8527 samples) could be included in our pooled analysis, while five additional documents provided diagnostic accuracy data but could not be extracted for construction of a 2 × 2 table. The pooled diagnostic sensitivity and specificity were 0.86 (95%CI, 0.84-0.88) and 0.99 (95%CI, 0.98-0.99), respectively, while the area under the summary receiver operating characteristic curve was 0.974 (95%CI, 0.965-0.983) and the agreement was 96.8% (95%CI, 96.4-97.1%), with kappa statistics of 0.87 (95%CI, 0.85-0.88). In conclusion, the diagnostic performance of the LumiraDX SARS-CoV-2 Antigen Test would allow the conclusion that it may be seen as a reliable alternative to molecular testing for the rapid preliminary screening of acute SARS-CoV-2 infections.

Background: Coronavirus disease-2019 (COVID-19) is associated with a high risk of acute kidney injury (AKI), often requiring renal replacement therapy (RRT). Serum Cystatin C (sCysC) and serum Neutrophil Gelatinase-Associated Lipocalin (sNGAL) are emerging biomarkers for kidney injury, and were suggested to be superior to serum creatinine (sCr) in several clinical settings. Moreover, elevated sCysC is associated with disease severity and mortality in COVID-19. We aimed to assess the utility of sCysC and sNGAL for predicting COVID-19-associated AKI, need for RRT, and need for intensive care unit (ICU) admission, when measured at presentation to the emergency department (ED)., Methods: Patients presenting to the ED with laboratory-confirmed COVID-19 were included. The primary outcome was development of COVID-19-associated AKI, while the secondary outcomes were need for RRT and ICU admission., Results: Among 52 COVID-19 patients, 22 (42.3%) developed AKI with 8/22 (36.4%) requiring RRT. Both sCr and sCysC demonstrated excellent performance for predicting AKI (AUC, 0.86 and 0.87, respectively) and need for RRT (AUC, 0.94 and 0.95, respectively). sNGAL displayed acceptable performance for predicting AKI (AUC, 0.81) and need for RRT (AUC, 0.87)., Conclusions: SCr and sCysC measured at ED presentation are both highly accurate predictors of AKI and need for RRT, whereas sNGAL demonstrated adequate diagnostic performance. While sCyC was previously shown to be superior to sCr as a diagnostic biomarker of kidney injury in certain etiologies, our findings demonstrate that sCr is comparable to sCyC in the context of predicting COVID-19-associated AKI. Given the high sensitivity of these biomarkers for predicting the need for RRT, and as sCysC is associated with mortality in COVID-19 patients, we recommend their measurement for enabling risk stratification and early intervention., (Copyright © 2022. Published by Elsevier Inc.)

Admission hyperglycemia has emerged worldwide as a predictor of poor coronavirus disease 2019 (COVID-19) outcome. Hyperglycemia leads to a defect in circulating hematopoietic stem/progenitor cells (HSPCs), which, in turn, predicts diabetic complications. Here, we explored whether reduced HSPCs mediated at least part of the prognostic effect of hyperglycemia on COVID-19 outcome. We found that patients with COVID-19 (n = 100) hospitalized in a nonintensive setting displayed dramatically (50-60%) reduced levels of HSPCs measured by flow cytometry as CD34+, CD34+CD45dim, or CD34+CD133+ cells, compared with control subjects (n = 595). This finding was highly significant (all P < 10-10) after multivariable adjustment, or manual 1:1 patient match, or propensity score matching. Admission hyperglycemia (≥7.0 mmol/L) was present in 45% of patients, was associated with a significant further ∼30% HSPCs reduction, and predicted a 2.6-fold increased risk of the primary outcome of adverse COVID-19 course (admittance to the intensive care unit or death). Low HSPCs were also associated with advanced age, higher peak C-reactive protein, and neutrophil-to-lymphocyte ratio. Independently from confounders, 1 SD lower CD34+ HSPCs was associated with a more than threefold higher risk of adverse outcome. Upon formal analysis, reduction of HSPCs was a significant mediator of the admission hyperglycemia on COVID-19 outcome, being responsible for 28% of its prognostic effect., (© 2022 by the American Diabetes Association.)

Competing Interests: Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-22-1104/coif). The series “Column in Laboratory Medicine” was commissioned by the editorial office without any funding or sponsorship. GL serves as the unpaid Guest Editor of the series. The authors have no other conflicts of interest to declare.

Background and Aims: Performance of two disposable devices for identifying subjects with low anti-SARS-CoV-2 protection was compared with that of automated enzyme-linked immunosorbent (ELISA) and chemiluminescent (CLIA) assay., Materials and Methods: In July 2021, 123 healthcare workers (HCW), twice vaccinated by BNT162b2/Comirnaty mRNA (BioNTech-Pfizer), underwent Ab iRapid COVID-19 Quant "Neutralizing" Self-test (iRapid Self-test) and "Neutralizing" Professional-use (iRapid pro) (DIESSE, Diagnostica Senese, Siena, Italy). Simultaneously, serum Ab were determined by Maglumi 2000 plus (anti S-RBD CLIA assay, Snibe Diagnostics, Shenzhen, China) and SARS-CoV-2 "Neutralizing" Ab Chorus ELISA (DIESSE, Siena, Italy). Results were evaluated against two "protective-thresholds", 90 kBAU/L and 506 kBAU/L., Results: HCW mean age, 46.2 (±12.6) years; 26 (20.5%), males, 101 (79.5%), females. The mean time interval (and standard deviation) between the first vaccine dose and Ab determination was 129.5 (±36.4) days and was neither gender (p = 0.879) nor age (p = 0.341) related. With Maglumi, 114 (89.7%) and 43 (33.8%) HCW presented Ab ≥ 90 kBAU/L and Ab ≥ 506 kBAU/L, respectively; with Chorus, 96 (75.6%) presented Ab values ≥506 kBAU/L. CLIA and ELISA agreement was 56.7%. At 90 kBAU/L, iRapid self-test and Pro sensitivities were 98.2% (95% CI: 92.7-99.8), specificity 69.2% (95% CI: 38.6-90.9%) and 76.9% (46.2-95%), respectively. At 506 kBAU/L, iRapid sensitivities were 58.1-91.6%, and specificities, 89-96.6%. On evaluating Ab at <4 and ≥4 months, protective titers had decreased., Conclusions: iRapid semi-quantitative devices had very good overall agreements of 95.1% and 95.9% for detecting individuals with low anti-SARS-CoV-2 protection., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Several studies shed light on the interplay among inflammation, thrombosis, multi-organ failures and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Increasing levels of both free and/or circulating histones have been associated to coronavirus disease 2019 (COVID-19), enhancing the risk of heart attack and stroke with coagulopathy and systemic hyperinflammation. In this view, by considering both the biological and clinical rationale, circulating histones may be relevant as diagnostic biomarkers for stratifying COVID-19 patients at higher risk for viral sepsis, and as predictive laboratory medicine tool for targeted therapies.

Immunoassays are currently the methods of choice for the measurement of a large panel of complex and heterogenous molecules owing to full automation, short turnaround time, high specificity and sensitivity. Despite remarkable performances, immunoassays are prone to several types of interferences that may lead to harmful consequences for the patient (e.g., prescription of an inadequate treatment, delayed diagnosis, unnecessary invasive investigations). A systematic search is only performed for some interferences because of its impracticality in clinical laboratories as it would notably impact budget, turnaround time, and human resources. Therefore, a case-by-case approach is generally preferred when facing an aberrant result. Hereby, we review the current knowledge on immunoassay interferences and present an algorithm for interference workup in clinical laboratories, from suspecting their presence to using the appropriate tests to identify them. We propose an approach to rationalize the attitude of laboratory specialists when faced with a potential interference and emphasize the importance of their collaboration with clinicians and manufacturers to ensure future improvements., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

We provide here a pooled analysis of accuracy of Fujirebio Lumipulse SARS-CoV-2 Antigen chemiluminescent immunoassay for diagnosing acute SARS-CoV-2 infections. An electronic search was conducted in Scopus and Medline with the keywords "Lumipulse" AND "antigen" AND "SARS-CoV-2" or "COVID-19", up to January 21, 2022, for identifying clinical investigations (minimum sample size ≥100) where diagnostic accuracy of Lumipulse G SARS-CoV-2 Ag was tested against reference molecular techniques. All studies which allowed to construct a 2 × 2 table were included in a pooled analysis. A final number of 21 studies, totalling 17,648 nasopharyngeal and 8538 saliva specimens, were finally included. The pooled diagnostic sensitivity and specificity in nasopharyngeal swabs were 0.80 (95%CI, 0.78-0.81) and 0.98 (95%CI, 0.97-0.98), respectively, whilst the area under the curve and agreement were 0.980 (95%CI, 0.973-0.986) and 94.9%, respectively. In the twelve studies which used the fixed 1.34 pg/mL currently recommended manufacturer's threshold, the diagnostic accuracy remained unvaried. In saliva samples, the pooled diagnostic sensitivity and specificity were 0.75 (95%CI, 0.71-0.75) and 1.00 (95%CI, 0.99-1.00), respectively, whilst the area under the curve and were 0.976 (95%CI, 0.969-0.984) and 98.4%, respectively. In the five studies which used the fixed 0.67 pg/mL currently recommended manufacturer's threshold, the diagnostic accuracy remained unvaried. In conclusion, Lumipulse G SARS-CoV-2 Ag assay demonstrates good diagnostic sensitivity and specificity, thus representing a valuable complementary and integrative option to molecular testing for SARS-CoV-2 in the current pandemic., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Since the beginning of laboratory medicine, the main focus was to provide high quality analytics. Over time the importance of the extra-analytical phases and their contribution to the overall quality became evident. However, as the initial preanalytical processes take place outside of the laboratory and mostly without its supervision, all professions participating in these process steps, from test selection to sample collection and transport, need to engage accordingly. Focusing solely on intra-laboratory processes will not be sufficient to achieve the best possible preanalytical quality. The Working Group for the Preanalytical Phase (WG-PRE) of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) has provided several recommendations, opinion papers and scientific evidence over the past years, aiming to standardize the preanalytical phase across Europe. One of its strategies to reach this goal are educational efforts. As such, the WG-PRE has organized five conferences in the past decade with the sole focus on preanalytical quality. This year's conference mainly aims to depict the views of different professions on preanalytical processes in order to acquire common ground as basis for further improvements. This article summarizes the content of this 6th preanalytical conference., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Clinical practice guidelines (CPGs) on screening, surveillance, and treatment of several diseases recommend the selective use of biomarkers with central role in clinical decision-making and move towards including patients in this process. To this aim we will clarify the multidisciplinary interactions required to properly measure the cost-effectiveness of biomarkers with regard to the risk-benefit of the patients and how Health Technology Assessment (HTA) approach may assess value of biomarkers integrated within the decision-making process. HTA through the interaction of different skills provides high-quality research information on the effectiveness, costs, and impact of health technologies, including biomarkers. The biostatistical methodology is relevant to HTA but only meta-analysis is covered in depth, whereas proper approaches are needed to estimate the benefit-risk balance ratio. Several biomarkers underwent HTA evaluation and the final reports have pragmatically addressed: 1) a redesign of the screening based on biomarker; 2) a de-implementation/replacement of the test in clinical practice; 3) a selection of biomarkers with potential predictive ability and prognostic value; and 4) a stronger monitoring of the appropriateness of test request. The COVID-19 pandemic has disclosed the need to create a robust and sustainable system to urgently deal with global health concerns and the HTA methodology enables rapid cost-effective implementation of diagnostic tests allowing healthcare providers to make critical patient-management decisions., (© 2022 Simona Ferraro et al., published by De Gruyter, Berlin/Boston.)

Purpose: Differentiated thyroid cancer (DTC) is the most common endocrine neoplasm, with a rising incidence and a long life expectancy. It has recently been suggested that patients with low- and intermediate-risk DTC with a good response to treatment at one year could be followed up using only highly sensitive immunoassays for thyroglobulin (Tg). The aim of this study was to examine the serum Tg levels in a series of DTC patients with histologically proven persistent or recurrent diseases., Methods: The study involved 50 consecutive patients being routinely followed up at our center, whose clinical, histological, and biochemical data were retrospectively collected., Results: The false-negative rate of ultrasensitive serum Tg assay was 14.3% (5/35) overall, and limited to anti-thyroglobulin autoantibodies (TgAb)-negative patients. Among them, only one patient had an excellent response to treatment at one-year follow-up and was diagnosed with a 4 mm recurrence, after more than seven years of periodic ultrasounds. The size of the neck lesion documented in the histological report was slightly larger in patients with detectable as opposed to negative Tg values (P < 0.05)., Conclusions: Serum highly sensitive Tg is undetectable in a proportion of patients with a proven persistent or recurrent DTC. The reasons behind this phenomenon are still unknown. However, in low/intermediate-risk patients cured at one-year follow-up, highly sensitive Tg without neck US seems an appropriate strategy for patients' management., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The relationship between diabetes mellitus and Parkinson's disease has been described in several epidemiological studies over the 1960s to date. Molecular studies have shown the possible functional link between insulin and dopamine, as there is strong evidence demonstrating the action of dopamine in pancreatic islets, as well as the insulin effects on feeding and cognition through central nervous system mechanism, largely independent of glucose utilization. Therapies used for the treatment of type 2 diabetes mellitus appear to be promising candidates for symptomatic and/or disease-modifying action in neurodegenerative diseases including Parkinson's disease, while an old dopamine agonist, bromocriptine, has been repositioned for the type 2 diabetes mellitus treatment. This review will aim at reappraising the different studies that have highlighted the dangerous liaisons between diabetes mellitus and Parkinson's disease., Competing Interests: None

Background: The active surveillance of students is proposed as an effective strategy to contain SARS-CoV-2 spread and prevent schools' closure. Saliva for molecular testing is as sensitive as naso-pharyngeal swab (NPS), self-collected and well accepted by participants. This prospective study aimed to verify whether the active surveillance of the Padua University employees by molecular testing of self-collected saliva is an effective and affordable strategy for limiting SARS-CoV-2 spread., Methods: A surveillance program based on self-collection of saliva every 2 weeks (October 2020-June 2021) was conducted. Among 8183 employees of the Padua University, a total of 6284 subjects voluntarily took part in the program. Eight collection points guaranteed the daily distribution and collection of barcoded salivary collection devices, which were delivered to the laboratory by a transport service for molecular testing. Quarantine of positive cases and contact tracing were promptly activated., Results: Among 6284 subjects, 206 individuals were SARS-CoV-2 positive (99 by salivary testing; 107 by NPS performed for contact tracing or symptoms). The cumulative SARS-CoV-2 incidence in this cohort was 3.1%, significantly lower than that of employees not in surveillance (8.0%), in Padua (7.1%) and in the Veneto region (7.2%). Employees with positive saliva results were asymptomatic or had mild symptoms. The levels of serum antibodies after 3 months from the infection were correlated with age and Ct values, being higher in older subjects with greater viral loads., Conclusions: Salivary-based surveillance with contact tracing effectively allowed to limit SARS-CoV-2 contagion, also in a population with a high incidence., (© 2022. The Author(s).)

Measuring the level of protection conferred by anti-SARS-CoV-2 (trimeric) spike or RBD (receptor binding domain) antibodies (especially total and IgG) is a suitable and reliable approach for predicting biological protection against the risk of infection and severe coronavirus disease 2019 (COVID-19) illness. Nonetheless, SARS-CoV-2 has undergone a broad process of recombination since the identification of the prototype lineage in 2019, introducing a huge number of mutations in its genome and generating a vast array of variants of interest (VoI) and concern (VoC). Many of such variants developed several mutations in spike protein and RBD, with the new Omicron (B.1.1.529) clade displaying over 30 changes, 15 of which concentrated in the RBD. Besides their impact on virus biology, as well as on the risk of detection failure with some molecular techniques (i.e., S  gene dropout), recent evidence suggests that these mutations may also jeopardize the reliability of currently available commercial immunoassays for detecting anti-SARS-CoV-2 antibodies. The antigen (either spike or RBD) and epitopes of the prototype SARS-CoV-2 coated in some immunoassays may no longer reflect the sequence of circulating variants. On the other hand, anti-SARS-CoV-2 antibodies elicited by highly mutated SARS-CoV-2 variants may no longer be efficiently recognized by the currently available commercial immunoassays. Therefore, beside the compelling need to regularly re-evaluate and revalidate all commercially available immunoassays against live virus neutralization assays based on emerging VoCs or VoIs, diagnostic companies may also consider to redevelop their methods, replacing former SARS-CoV-2 antigens and epitopes with those of the new variants., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

Background: To date, there's no evidence of an increased risk of SARS-CoV-2 infection or more severe COVID-19 in patients with inflammatory bowel disease (IBD). However, whether COVID-19 alters the clinical course of IBD or whether IBD treatment affects the immunological response to SARS-CoV-2 is still under investigation, especially in children., Aim: To assess the serological response to SARS-CoV-2 in children with IBD, and to evaluate the impact of COVID-19 on the clinical course of IBD., Material and Methods: This prospective study enrolled children (0-18 years) followed-up at the University Hospital of Padova for IBD, who acquired a confirmed SARS-CoV-2 infection between 02.2020 and 02.2021. The anti-SARS-CoV-2 S-RBD IgG titer was evaluated at 3 months after infection and compared to that of a control group of healthy children matched for age, sex, and COVID-19 severity., Results: Twelve children with IBD ( M = 5; median age 14 years) contracted COVID-19 during the study period. 11/12 patients were under immunomodulatory treatment (4/12 steroids; 6/12 azathioprine; 3/12 anti-TNFs; 2 vedolizumab; 1 ustekinumab). SARS-CoV-2 infection remained asymptomatic in 4/12 children and caused mild COVID-19 in the remaining 8. Mean anti-SARS-CoV-2 IgG S-RBD titer was similar between IBD patients and controls (27.3 ± 43.8 vs. 36.8 ± 35.3 kAU/L, p = ns). No children experienced IBD flares nor required gastroenterological support during the infection period., Discussion: Children with IBD can mount a protective humoral response against SARS-CoV-2, which is comparable to that of their healthy peers regardless of ongoing immunomodulatory treatment. This study also supports the favorable course of PIBD during COVID-19 and vice-versa., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Bosa, Di Chiara, Gaio, Cosma, Padoan, Cozzani, Perilongo, Plebani, Giaquinto, Donà and Cananzi.)

Purpose of Review: We describe the mechanism of action of vitamin K, and its implication in cardiovascular disease, bone fractures, and inflammation to underline its protective role, especially in chronic kidney disease (CKD)., Recent Findings: Vitamin K acts as a coenzyme of y-glutamyl carboxylase, transforming undercarboxylated in carboxylated vitamin K-dependent proteins. Furthermore, through the binding of the nuclear steroid and xenobiotic receptor, it activates the expression of genes that encode proteins involved in the maintenance of bone quality and bone remodeling. There are three main types of K vitamers: phylloquinone, menaquinones, and menadione. CKD patients, for several conditions typical of the disease, are characterized by lower levels of vitamin K than the general populations, with a resulting higher prevalence of bone fractures, vascular calcifications, and mortality. Therefore, the definition of vitamin K dosage is an important issue, potentially leading to reduced bone fractures and improved vascular calcifications in the general population and CKD patients., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: The Careggi Collateral Score (CCS) (qualitative-quantitative evaluation) was developed from a single-centre cohort as an angiographic score to describe both the extension and effectiveness of the pial collateral circulation in stroke patients with occlusion of the anterior circulation. We aimed to examine the association between CCS (quantitative evaluation) and 3-month modified Rankin Scale (mRS) score in a large multi-center cohort of patients receiving thrombectomy for stroke with occlusion of middle cerebral artery (MCA)., Methods: We conducted a study on prospectively collected data from 1284 patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke. According to the extension of the retrograde reperfusion in the cortical anterior cerebral artery (ACA)-MCA territories, CCS ranges from 0 (absence of retrograde filling) to 4 (visualization of collaterals until the alar segment of the MCA)., Results: Using CCS of 4 as reference, CCS grades were associated in the direction of unfavourable outcome on 3-month mRS shift (0 to 6); significant difference was found between CCS of 0 and CCS of 1 and between CCS of 3 and CCS of 4. CCS ≥ 3 was the optimal cut-off for predicting 3-month excellent outcome, while CCS ≥ 1 was the optimal cut-off for predicting 3-month survival. CCS of 0 and CCS < 3 were associated in the direction of unfavourable recanalization on TICI shift (0 to 3) compared with CCS ≥ 1 and CCS ≥ 3, respectively. Compared with CCS ≥ 3 as reference, CCS of 0 and CCS 1 to 2 were associated in the direction of unfavourable recanalization on TICI shift. There was no evidence of heterogeneity of effects of successful recanalization and procedure time ≤ 60 min on 3-month mRS shift across CCS categories., Conclusion: The CCS could provide a future advantage for improving the prognosis in patients receiving thrombectomy for stroke with M1 or M1-M2 segment of the MCA occlusion., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Objectives: The reliable identification of individuals with SARS-CoV-2 infection is the cornerstone for containing viral spread. Rapid molecular point-of-care testing (POCT) of saliva might reduce analysis time, thus increasing the efficacy of contact tracing. In this study, a new POCT RT-PCR assay for the detection of SARS-CoV-2 RNA in saliva was evaluated and compared with an already validated CE-IVD method., Methods: An evaluation was made of 160 left-over salivary samples (27 frozen, kept at -80 °C and 133 fresh), collected using Salivette (Sarstedt, Germany). Samples were analyzed by TaqPath COVID-19 CE-IVD RT-PCR kit, QuantStudio5 Real-Time (Applied Biosystems, USA) (TaqPath) and bKIT Virus Finder COVID-19 Saliva (Hyris Global Diagnostics, Italy). Performances of three- and fivefold pooling strategies were also evaluated. Blood assay interference in saliva was also tested with Hyris., Results: On using TaqPath, SARS-CoV-2 positivity was detected in 35 samples. Another 10 positive samples were artificially-generated by blind mixing of positive with negative samples. Hyris positive and negative percentages of agreement were 97.6 (95% CI: 87.2-99.9%) and 100 (95% CI: 97.0-100%), respectively. Seventeen positive pools, evaluated for threefold strategy, were all correctly determined by both systems. For the 5-pool strategy, 94.7% (18/19) of samples resulted positive with the Hyris system, and 100% with TaqPath. The presence of 1% of blood (v/v) in saliva did not interfere with the accuracy of Hyris assay., Conclusions: The sensitivity and specificity of the bKIT Virus Finder COVID-19 Saliva were optimal with respect to TaqPath. In view of the safe and straightforward pre-analytical procedure involved, and the small size of the Hyris bCube, the Hyris system can be used for POCT., (© 2022 Andrea Padoan et al., published by De Gruyter, Berlin/Boston.)

Objectives: Delta check (DC) is widely used for detecting sample mix-up. Owing to the inadequate error detection and high false-positive rate, the implementation of DC in real-world settings is labor-intensive and rarely capable of absolute detection of sample mix-ups. The aim of the study was to develop a highly accurate DC method based on designed deep learning to detect sample mix-up., Methods: A total of 22 routine hematology test items were adopted for the study. The hematology test results, collected from two hospital laboratories, were independently divided into training, validation, and test sets. By selecting six mainstream algorithms, the Deep Belief Network (DBN) was able to learn error-free and artificially (intentionally) mixed sample results. The model's analytical performance was evaluated using training and test sets. The model's clinical validity was evaluated by comparing it with three well-recognized statistical methods., Results: When the accuracy of our model in the training set reached 0.931 at the 22nd epoch, the corresponding accuracy in the validation set was equal to 0.922. The loss values for the training and validation sets showed a similar (change) trend over time. The accuracy in the test set was 0.931 and the area under the receiver operating characteristic curve was 0.977. DBN demonstrated better performance than the three comparator statistical methods. The accuracy of DBN and revised weighted delta check (RwCDI) was 0.931 and 0.909, respectively. DBN performed significantly better than RCV and EDC. Of all test items, the absolute difference of DC yielded higher accuracy than the relative difference for all methods., Conclusions: The findings indicate that input of a group of hematology test items provides more comprehensive information for the accurate detection of sample mix-up by machine learning (ML) when compared with a single test item input method. The DC method based on DBN demonstrated highly effective sample mix-up identification performance in real-world clinical settings., (© 2021 Rui Zhou et al., published by De Gruyter, Berlin/Boston.)

Serial measurements of cardiac troponin are recommended by international guidelines to diagnose myocardial infarction (MI) since 2000. However, some relevant differences exist between the three different international guidelines published between 2020 and 2021 for the management of patients with chest pain and no ST-segment elevation. In particular, there is no agreement on the cut-offs or absolute change values to diagnose non-ST-segment elevation MI (NSTEMI). Other controversial issues concern the diagnostic accuracy and cost-effectiveness of cut-off values for the most rapid algorithms (0 h/1 h or 0 h/2 h) to rule-in and rule-out NSTEMI . Finally, another important point is the possible differences between demographic and clinical characteristics of patients enrolled in multicenter trials compared to those routinely admitted to the Emergency Department in Italy. The Study Group of Cardiac Biomarkers, supported by the Italian Scientific Societies Società Italiana di Biochimica Clinica, Italian Society of the European Ligand Assay Society, and Società Italiana di Patolgia Clinica e Medicina di Laboratorio decided to revise the document previously published in 2013 about the management of patients with suspected NSTEMI, and to provide some suggestions for the use of these biomarkers in clinical practice, with a particular focus on the Italian setting., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

Objectives: mRNA vaccines, including Comirnaty (BNT162b2 mRNA, BioNTech-Pfizer), elicit high IgG and neutralizing antibody (NAb) responses after the second dose, but the progressive decrease in serum antibodies against SARS-CoV-2 following vaccination have raised questions concerning long-term immunity, decreased antibody levels being associated with breakthrough infections after vaccination, prompting the consideration of booster doses., Methods: A total number of 189 Padua University-Hospital healthcare workers (HCW) who had received a second vaccine dose were asked to collect serum samples for determining Ab at 12 (t 12 ) and 28 (t 28 ) days, and 6 months (t 6m ) after their first Comirnaty/BNT162b2 inoculation. Ab titers were measured with plaque reduction neutralization test (PRNT), and three chemiluminescent immunoassays, targeting the receptor binding domain (RBD), the trimeric Spike protein (trimeric-S), and surrogate viral neutralization tests (sVNT)., Results: The median percentages (interquartile range) for decrease in antibodies values 6 months after the first dose were 86.8% (67.1-92.8%) for S-RBD IgG, 82% (58.6-89.3%) for trimeric-S, 70.4% (34.5-86.4%) for VNT-Nab, 75% (50-87.5%) for PRNT 50 and 75% (50-93.7%) for PRNT 90 . At 6 months, neither PRNT titers nor VNT-Nab and S-RBD IgG bAb levels correlated with age (p=0.078) or gender (p=0.938), while they were correlated with previous infection (p<0.001)., Conclusions: After 6 months, a method-independent reduction of around 90% in anti-SARS-CoV-2 antibodies was detected, while no significant differences were found between values of males and females aged between 24 and 65 years without compromised health status. Further efforts to improve analytical harmonization and standardization are needed., (© 2021 Andrea Padoan et al., published by De Gruyter, Berlin/Boston.)

Background: Studies evaluating neutralizing antibody (NAb) after BNT162b2 vaccine are scarce. We therefore compared NAb using the plaque reduction neutralization test (PRNT) in vaccinated subjects, with those from five chemiluminescent (CLIA) assays, two targeting ACE and S-RBD interaction., Methods: Sera from 174 completely Comirnaty/BNT162b2 vaccinated healthcare workers (HCW) were evaluated at t 12 and t 28 . NAb titers at low (PRNT 50 ) or high (PRNT 90 ) stringency were compared with: Liaison SARS-CoV-2 Trimeric-S IgG, Elecsys S-RBD Ab, Maglumi SARS-CoV-2 S-RBD IgG and SARS-CoV-2 Nab; iFlash 2019-nCoV NAb., Results: Neither PRNT 50 nor PRNT 90 correlated with age (range, 24-65 years); no significant differences were found for gender. PRNT 50 and PRNT 90 seropositive titers (≥1:20) were 43 (24.7%) and 15 (8.6%) at t 12 and 167 (95.9%) and 149 (85.6%) at t 28 . CLIA results at t 28 were uncorrelated with age, apart from Elecsys S-RBD Ab (r = -0.164, p = 0.046). Gender differences were found for Maglumi SARS-CoV-2 S-RBD IgG (p = 0.037) and Maglumi NAb (p = 0.046). Considering PRNT 50 at thresholds of 1:20 (or 1:40) and 1:160 (or 1:320), corresponding to different immune protective levels, CLIA cut-offs have been identified., Conclusions: Comirnaty/BNT162b2 elicits strong NAb production, especially 28 days after first inoculum. Differences in correlation between Nab titers and circulating antibodies measured by 5 immunoassays have been found, being stronger the correlation for Maglumi Nab., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Endothelial dysfunction, a major complication of SARS-CoV-2 infectionplaying a key-role in multi-organ damage, carries high risk of mortality., Aim: To investigate the potential role of Mid-Regional pro-Adrenomedullin (MR-proADM) in detecting endothelial damage with a view to stratifying the risk of adverse events (length of stay, death, admission in Intensive Care Unit) and/or disease resolution., Materials and Methods: In 135 consecutive patients with SARS-CoV-2 infection, MR-proADM was measured in EDTA-K2 plasma samples using B.R.A.H.M.S. KRYPTOR® COMPACT Plus method (Thermo Fisher Scientific, Hennigsdorf, Germany) RESULTS: Patients were subdivided into three groups based on their MR-proADM value (nmol/L): 1 (n = 20, MR-proADM ≤ 0.55); 2 (n = 82, 0.55 < MR-proADM ≤ 1.50); 3 (n = 33, MR-proADM > 1.50). The higher the MR-proADM value, the greater the patients' age, the more frequent the occurrence of pneumonia, the requiring of more aggressive treatment, the longer the hospitalization and the more frequent a fatal event. Significant differences were found between the three groups for MR-proADM, White-blood cell count, Neutrophil count, D-dimer, C-reactive Protein, Procalcitonin and hs-Troponin I. At logistic regression,it was found that MR-proADM and Log 10 D-dimer were the most significant predictors of adverse events., Conclusion: The findings made in the present study highlight the relevance of MR-proADM values in providing clinically useful information, particularly for stratifying COVID-19 patients according to the risk of a more severe form of disease and to the development of adverse events., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Fractures and vascular calcifications (VCs) are common in patients with chronic kidney disease (CKD). They are related to abnormalities in vitamin D metabolism, calcium, phosphorus, parathyroid hormone, and fibroblast growth factor 23 (FGF23)/Klotho that occur with CKD. Impaired vitamin D metabolism and abnormal levels of calcium, phosphate, parathyroid hormone (PTH), and FGF23/Klotho drive bone and vascular changes in CKD. It is unclear if oral calcitriol safely mitigates fracture risk without increasing the burden of calcifications. Therefore, we investigated whether treatment with calcitriol affected the prevalence of fractures and VC progression in hemodialysis (HD) patients. This report is a secondary analysis of the Vitamin K Italian (VIKI) study, a cross-sectional study involving 387 HD patients. We assessed vitamin 25(OH)D, alkaline phosphatase, PTH, calcium, phosphate, osteocalcin or bone Gla protein, matrix Gla protein, and vitamin K levels. Vertebral fractures (VFs) and VCs were determined by spine radiograph. A reduction of >20% of vertebral body height was considered a VF. VCs were quantified by the length of calcific lesions along the arteries. The patients treated with oral calcitriol were 177 of 387 patients (45.7%). The prevalence of VF was lower in patients receiving oral calcitriol than in those untreated (48.6% versus 61.0%, p = 0.015), whereas the presence of aortic and iliac calcifications was similar (aortic: 81.9% versus 79.5%, respectively, p = 0.552; iliac: 52.0% and 59.5%, respectively, p = 0.167). In multivariable logistic regression analysis, oral calcitriol was associated with a 40.2% reduced odds of fracture (OR 0.598; 95% confidence interval [CI], 0.363-0.985; p = 0.043). In conclusion, we found a significant association between oral calcitriol and lower VF in HD patients without an increase in the burden of VC. Further prospective and interventional studies are needed to confirm these findings. © 2021 American Society for Bone and Mineral Research (ASBMR)., (© 2021 American Society for Bone and Mineral Research (ASBMR).)

Background: Heart involvement (HInv) in systemic sclerosis (SSc) may relate to myocarditis and is associated with poor prognosis. Serum anti-heart (AHA) and anti-intercalated disk autoantibodies (AIDA) are organ and disease-specific markers of isolated autoimmune myocarditis. We assessed frequencies, clinical correlates, and prognostic impacts of AHA and AIDA in SSc., Methods: The study included consecutive SSc patients ( n = 116, aged 53 ± 13 years, 83.6% females, median disease duration 7 years) with clinically suspected heart involvement (symptoms, abnormal ECG, abnormal troponin I or natriuretic peptides, and abnormal echocardiography). All SSc patients underwent CMR. Serum AHA and AIDA were measured by indirect immunofluorescence in SSc and in control groups of non-inflammatory cardiac disease (NICD) ( n = 160), ischemic heart failure (IHF) ( n = 141), and normal blood donors (NBD) ( n = 270). AHA and AIDA status in SSc was correlated with baseline clinical, diagnostic features, and outcome., Results: The frequency of AHA was higher in SSc (57/116, 49%, p < 0.00001) than in NICD (2/160, 1%), IHF (2/141, 1%), or NBD (7/270, 2.5%). The frequency of AIDA was higher (65/116, 56%, p < 0.00001) in SSc than in NICD (6/160, 3.75%), IHF (3/141, 2%), or NBD (1/270, 0.37%). AHAs were associated with interstitial lung disease ( p = 0.04), history of chest pain ( p = 0.026), abnormal troponin ( p = 0.006), AIDA ( p = 0.000), and current immunosuppression ( p = 0.01). AHAs were associated with death ( p = 0.02) and overall cardiac events during follow-up ( p = 0.017)., Conclusions: The high frequencies of AHA and AIDA suggest a high burden of underdiagnosed autoimmune HInv in SSc. In keeping with the negative prognostic impact of HInv in SSc, AHAs were associated with dismal prognosis.

Background: Studies reporting the long-term humoral response after receiving the BNT162b2 COVID-19 vaccine are important to drive future vaccination strategies. Yet, available literature is scarce. Covidiagnostix is a multicenter study designed to assess the antibody response in >1000 healthcare professionals (HCPs) who received the BNT162b2 vaccine., Methods: Serum was tested at time-0 (T 0 ), before the first dose, T 1 , T 2, and T 3 , respectively, 21, 42, and 180 days after T 0 . Antibodies against the SARS-CoV-2 nucleocapsid-protein were measured to assess SARS-CoV-2 infections, whereas antibodies against the receptor-binding domain of the spike protein were measured to assess the vaccine response. Neutralization activity against the D614G, B.1.1.7, and B.1.351 variants were also analyzed., Results: Six months post-vaccination HCPs showed an antibody titer decrease of approximately 70%, yet, the titer was still one order of magnitude higher than that of seropositive individuals before vaccination. We identified 12 post-vaccination infected HCPs. None showed severe symptoms. Interestingly, most of them showed titers at T 2 above the neutralization thresholds obtained from the neutralization activity experiments., Conclusion: Vaccination induces a humoral response which is well detectable even six months post-vaccination. Vaccination prevents severe COVID-19 cases, yet post-vaccination infection is possible even in the presence of a high anti-S serum antibody titer.

To report our experience in treating one patient with nontraumatic subarachnoid hemorrhage (SAH) and concurrent acute ischemic stroke (AIS) due to large vessels occlusion (LVO). A man in his 50 s presented with acute right hemiparesis and aphasia. Brain CT showed a SAH in the left central sulcus; CT-angiography revealed a tandem occlusion of the left internal carotid artery and homolateral middle cerebral artery. He underwent an angiographic procedure with successful recanalization. Follow-up CT demonstrated a striatal-lenticular stroke without SAH progression. While the absolute contraindication to IVT during intracranial bleeding remains unquestionable, the potential injury/benefit from MT is still debatable. Such cases constitute a blind spot in the guidelines where physicians face the dilemma of choosing between an acute endovascular treatment with the risks of hemorrhage progression and a conservative treatment with the associated poor clinical outcome. We decided to treat our patient invasively, considering the young age, also given the absence of prognostic factors that generally predict post-procedural reperfusion injury. We believe that, in similar cases, MT should be considered-despite not free of risks and drawbacks-to avoid the detrimental consequences of untreated AIS from LVO., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Success of adrenal vein sampling (AVS) is verified by the selectivity index (SI), i.e., by a step-up of cortisol levels between the adrenal vein and the infrarenal inferior vena cava samples, beyond a given cut-off. We tested the hypothesis that androstenedione, metanephrine, and normetanephrine, which have higher gradients than cortisol, could increase the rate of AVS studies judged to be bilaterally successful and usable for the clinical decision making. We prospectively compared within-patient, head-to-head, the selectivity index of androstenedione (SI A ), metanephrine (SI M ), and normetanephrine (SI NM ), and cortisol (SI C ) in consecutive hypertensive patients with primary aldosteronism submitted to AVS. Main outcome measures were rate of bilateral success, SI values, and identification of unilateral PA. We recruited 136 patients (55 + 10 years, 35% women). Compared to the SI C , the SI A values were 3.5-fold higher bilaterally, and the SI M values were 7-fold and 4.4-fold higher on the right and the left side, respectively. With the SI A and the SI M the rate of bilaterally successful AVS increased by 14% and 15%, respectively without impairing the identification of unilateral PA. We concluded that androstenedione and metanephrine outperformed cortisol for ascertaining AVS success, thus increasing the AVS studies useable for the clinical decision making.

Background: Procalcitonin (proCt) was recently proposed as an alternative or in addition to calcitonin (Ct) in medullary thyroid cancer (MTC) diagnostics., Methods: Serum basal Ct (bCt) and proCt (bproCt) levels were measured before surgery from a consecutive series of patients with (n=43) and without (n=75) MTC, retrospectively collected in Padua. Serum bproCt, bCt and stimulated proCt and Ct (sproCt and sCt) were measured in another consecutive series of 33 patients seen at three tertiary-level institutions undergoing a calcium stimulation test prior to surgery, 20 of them with a final diagnosis of MTC, and 13 with non-MTC nodular disease., Results: Median bproCt levels were higher in MTC than in non-MTC. A positive correlation was found for bproCt with bCt (P<0.01, R 2 = 0.75), and with tumor size (P<0.01, R 2 = 0.39). The cut-off for bproCt differentiating between MTC and non-MTC patients was >0.07 ng/ml (sensitivity: 85.7%, specificity: 98.9%, positive predictive value [PPV]: 98.2%, negative predictive value [NPV]: 90.6%, P<0.01). While bproCt was >0.07 ng/ml in 38/39 (97.4%) patients with MTC >10 mm, it was above said cut-off only in 15/23 (65.2%) patients with tumors ≤10 mm. A sproCt >0.19 ng/ml was able to identify MTC [sensitivity: 90.0%, specificity:100.0%, PPV: 100.0%, NPV: 86.7% (P<0.01)]., Conclusions: Our data suggest that bproCt can be a good adjunct to Ct for MTC diagnostic purposes. In consideration of its high specificity, it can be used in combination with Ct in MTC diagnostics, particularly in the case of mildly elevated basal Ct levels., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Censi, Di Stefano, Repaci, Benvenuti, Manso, Pagotto, Iacobone, Barollo, Bertazza, Galuppini, Benna, Pennelli, Plebani, Faggian, Colombo, Fugazzola and Mian.)

Vascular calcification and fragility fractures are associated with high morbidity and mortality, especially in end-stage renal disease. We evaluated the relationship of iliac arteries calcifications (IACs) and abdominal aortic calcifications (AACs) with the risk for vertebral fractures (VFs) in hemodialysis patients. The VIKI study was a multicenter cross-sectional study involving 387 hemodialysis patients. The biochemical data included bone health markers, such as vitamin K levels, vitamin K-dependent proteins, vitamin 25(OH)D, alkaline phosphatase, parathormone, calcium, and phosphate. VF, IACs and AACs was determined through standardized spine radiograms. VF was defined as >20% reduction of vertebral body height, and VC were quantified by measuring the length of calcium deposits along the arteries. The prevalence of IACs and AACs were 56.1% and 80.6%, respectively. After adjusting for confounding variables, the presence of IACs was associated with 73% higher odds of VF ( p = 0.028), whereas we found no association ( p = 0.294) for AACs. IACs were associated with VF irrespective of calcification severity. Patients with IACs had lower levels of vitamin K2 and menaquinone 7 (0.99 vs. 1.15 ng/mL; p = 0.003), and this deficiency became greater with adjustment for triglycerides (0.57 vs. 0.87 ng/mL; p < 0.001). IACs, regardless of their extent, are a clinically relevant risk factor for VFs. The association is enhanced by adjusting for vitamin K, a main player in bone and vascular health. To our knowledge these results are the first in the literature. Prospective studies are needed to confirm these findings both in chronic kidney disease and in the general population.

Background: The immune response plays a pivotal role in dictating the clinical outcome in severe acute respiratory syndrome coronavirus 2 (SARS - CoV - 2)-infected adults, but it is still poorly investigated in the pediatric population., Methods: Of 209 enrolled subjects, 155 patients were confirmed by PCR and/or serology as having coronavirus disease 2019 (COVID-19). Blood samples were obtained at a median of 2.8 (interquartile, 2.1-3.7) and 6.1 (5.3-7.2) months after baseline (symptom onset and/or first positive virus detection). The immune profiles of activation, senescence, exhaustion, and regulatory cells were analyzed by flow cytometry. Neutralizing antibodies (nAbs) were detected by a plaque reduction neutralization test. In available nasopharyngeal swabs at baseline, SARS-CoV-2 levels were quantified by digital droplet PCR (ddPCR)., Results: Overall, COVID-19 patients had higher levels of immune activation, exhaustion, and regulatory cells compared to non-COVID-19 subjects. Within the COVID-19 group, activated and senescent cells were higher in adults than in children and inversely correlated with the nAbs levels. Conversely, Tregs and Bregs regulatory cells were higher in COVID-19 children compared to adults and positively correlated with nAbs. Higher immune activation still persisted in adults after 6 months of infection, while children maintained higher levels of regulatory cells. SARS-CoV-2 levels did not differ among age classes., Conclusions: Adults displayed higher immune activation and lower production of anti-SARS-CoV-2 nAbs than children. The different immune response was not related to different viral load. The higher expression of regulatory cells in children may contribute to reduce the immune activation, thus leading to a greater specific response against the virus., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Petrara, Bonfante, Costenaro, Cantarutti, Carmona, Ruffoni, Di Chiara, Zanchetta, Barzon, Donà, Da Dalt, Bortolami, Pagliari, Plebani, Rossi, Cotugno, Palma, Giaquinto and De Rossi.)

Context: The low-dose short synacthen test (LDSST) is recommended for patients with suspected central adrenal insufficiency (AI) if their basal serum cortisol (F) levels are not indicative of an intact hypothalamic-pituitary-adrenal (HPA) axis., Objective: To evaluate diagnostic threshold for salivary F before and 30 min after administering 1 μg of synacthen, performed before 09:30 h., Design: A cross-sectional study from 2014 to 2020., Setting: A tertiary referral university hospital., Patients: In this study, 174 patients with suspected AI, 37 with central AI and 137 adrenal sufficient (AS), were included., Main Outcome Measure: The diagnostic accuracy (sensitivity (SE), specificity (SP)) of serum and salivary F levels measured, respectively, by chemiluminescence immunoassay and liquid chromatography-tandem mass spectrometry., Results: Low basal serum or salivary F levels could predict AI. For the LDSST, the best ROC-calculated threshold for serum F to differentiate AI from AS was 427 nmol/L (SE 79%, SP 89%), serum F > 500 nmol/L reached SP 100%. A salivary F peak > 12.1 nmol/L after administering synacthen reached SE 95% and SP 84% for diagnosing central AI, indicating a conclusive reduction in the likelihood of AI. This ROC-calculated threshold for salivary F was similar to the 2.5th percentile of patients with a normal HPA axis, so it was considered sufficient to exclude AI. Considering AS those patients with salivary F > 12.1 nmol/L after LDSST, we could avoid unnecessary glucocorticoid treatment: 99/150 subjects (66%) had an inadequate serum F peak after synacthen, but salivary F was >12.1 nmol/L in 79 cases, who could, therefore, be considered AS., Conclusions: Salivary F levels > 12.1 nmol/L after synacthen administration can indicate an intact HPA axis in patients with an incomplete serum F response, avoiding the need to start glucocorticoid replacement treatment.

In anticipation of an interseasonal respiratory syncytial virus (RSV) epidemic, a clinician-led reporting system was rapidly established to capture RSV infections in Swiss hospitals, starting in January 2021. Here, we present details of the reporting system and first results to June 2021. An unusual epidemiology was observed with an interseasonal surge of RSV infections associated with COVID-19-related non-pharmacological interventions. These data allowed real-time adjustment of RSV prophylaxis guidelines and consequently underscore the need for and continuation of systematic nationwide RSV surveillance.

Background: Recent evidence suggests that neutralizing antibodies (nAbs) to severe acute respiratory syndrome coronavirus 2 may persist over time; however, knowledge regarding pediatric subjects is limited., Methods: A single-center, prospective observational study was conducted on 57 family clusters of coronavirus disease 2019, including children of neonatal and pediatric age attending the University Hospital of Padua (Italy). For each patient, blood samples were collected for both the quantification of nAbs through a plaque reduction neutralizing test and the detection of antinucleocapsid-spike protein immunoglobulin G and/or immunoglobulin M., Results: We analyzed 283 blood samples collected from 152 confirmed coronavirus disease 2019 cases (82 parents and 70 children or older siblings of median age of 8 years, interquartile range: 4-13), presenting asymptomatic or with mildly symptomatic disease. Despite the decrease of immunoglobulin G over time, nAbs were found to persist up to 7 to 8 months in children, whereas adults recorded a modest declining trend. Interestingly, children aged <6 years, and, in particular, those aged <3 years, developed higher long-lasting levels of nAbs compared with older siblings and/or adults., Conclusions: Mild and asymptomatic severe acute respiratory syndrome coronavirus 2 infections in family clusters elicited higher nAbs among children., Competing Interests: POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2021 by the American Academy of Pediatrics.)

Objectives: Numerous analytical systems, rapidly made available on the market throughout the SARS-CoV-2 pandemic, aim to detect COVID-19, and to continuously update and improve the same systems. Medical laboratory professionals have also developed in-house analytical procedures in order to satisfy the enormous volume of requests for tests. These developments have highlighted the need control the analytical procedures used in order to guarantee patient safety. The External Quality Assessment (EQA) Scheme, an important quality assurance tool, aims to guarantee high standard performance for laboratory and analytical procedures. The aim of the present study was to report on the results collected in an experimental EQA scheme for the serological diagnosis of SARS-CoV-2., Methods: All qualitative results collected in the different EQA surveys were summarized in order to identify the percentage of laboratory results in relation to typology of antibodies, results and samples., Results: A total of 4,867 data sets were collected. The analysis of EQA data made, demonstrates a better agreement among laboratories results for total Ig than single immunoglobulins (IgG, IgM, IgA) in the case samples positive for SARS-CoV-2, and a wide divergence between IgM results for positive samples (only 34.9% were correct). Results for negative controls and specificity controls demonstrated a better overall agreement than results for positive samples., Conclusions: Working in collaboration with the IVD manufacturers, laboratory professionals must strive to achieve harmonization of results, and to develop well-defined protocols complying with the ISO 15189 requirements., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)