ABSTRACT
Introduction: SARS-CoV-2 immune-response is mediated by both humoral and cellular immunity. However, since Ab levels wane faster than SARS-CoV-2 specific T cells immunity, cellular immunity represents an important factor for COVID-19 immune defence. Determining immunoreactivity of SARS-CoV-2 specific T cells is of clinical relevance in transplant recipients or patients treated with immunomodulant therapy. SARS-CoV-2 specific T cells assays are currently based on ELISA, whilst rapid tests are pivotal for real-time patients' evaluation. In this study, a novel direct real-time PCR (dRT-PCR) targeting mRNA of CXCL10 for measuring SARS-CoV-2 specific T cells, was tested and evaluated. Method(s): A total of 104 healthcare workers, with two or three doses of homologous (Pfizer/BioNTech, n = 82) or heterologous (Pfizer/BioNTech and Vaxzevria or Moderna, n = 22) vaccinations were asked to collect a blood (Li-He) sample. Blood was stimulated overnight with SARS-CoV-2 spike peptides (S-peptide) or treated with non-stimulating substance. Stimulated/treated samples were diluted in Buffer A, mixed with dqTACT MS then loaded into the cartridge. The analysis was performed using SCV2 T Activation kit, bCube and bApp (Hyris srl, Lodi, Italy), equipped by an automatic result interpretation based on artificial intelligence. For a subgroup of 49 samples, IFN-y releases to SARS-CoV-2 spike peptides were tested by Quant-T-Cell SARS-CoV-2 and ELISA (Euroimmune, Lubeck, Germany). Result(s): Seventy-nine (75.9%) and 25 (24.1%) were females and males, respectively. Twenty-nine subjects were previously infected by SARS-CoV-2. Overall mean age (+/- SD) was 45.9+/-13.3 years. At qualitative analyses, 97 subjects (93.2%) resulted reactive to S-peptides, 3 (2.8%) were borderline and 4 were negative (3.8%). These negatives had their third vaccinal dose in December/November 2021. Previous infected individuals presented reactivity to S-peptides, with the exception of one subject with resulted reactive also in the untreated sample. Samples tested with both dRT-PCR and ELISA perfectly agreed (100%) with both methods. At quantitative analyses, between-assay correlation was 0.32 (p<0.001). Conclusion(s): Hyris dRT-PCR appeared accurate for determining presence or absence of immunoreactivity of SARS-CoV-2 specific T cell, especially when rapid analyses are required, such as for organ transplantation.
ABSTRACT
Background: The Severe Acute Respiratory Syndrome Coronavirus 2 related (SARS-CoV-2) has rapidly spread originating into the fifth documented pandemic wave. Dried blood spot (DBS) provides an alternative method to the venous blood samples to determine Ab, presenting several advantages, including the practicability, especially in infants, and the possibility to test a higher number of samples in a limited time. The main goal of this study was to measure seroprevalence of anti-SARS-CoV-2 IgG Ab in newborns, using DBS collected from January 2020 to December 2021. Method(s): Anti-SARS-CoV-2 IgG levels were determined using DBS by Anti-SARS-CoV-2 QuantiVac IgG ELISA assay (Euroimmune, Lubeck, Germany). Result(s): Preliminary analyses included 515 DBS from newborns, 54% males and 46% females, collected 2-3 days after birth. Overall, mean IgG levels, although below the positive threshold (>= 35.2 kBAU/L), were significantly higher in 2021 (Feb/21 and Mar/21), with respect to 2020 (Feb/20: 8.6+/-3.5, n=99 vs Feb/21: 28.1+/-42.8, n=40;Mar/20: 11.6+/-5.1, n=94 -Mar/21: 16.8+/-11.6, n=39, mean kBAU/L +/- DS, p<0.005). Moreover, an increased number of positive samples were found in 2021 (4/44 Gen/21;8/40 Feb/21;2/39 Mar/21). As expected, a trend of increase around 5% in DBS tested positive for anti-SARSCoV-2 IgG were found in December 2021, where IgG were above the positive threshold in 41.54% of DBS (450.926+/-873.291, mean kBAU/L +/- DS, n=65). Conclusion(s): In these preliminary data, newborn DBS seems to reflect population-wide infection rates during the studied periods. This suggests a potential role for DBS in COVID-19 surveillance, especially in infants and in areas where viral testing is limited.
ABSTRACT
Introduction: external Quality Assessment (EQA) is a valuable tool to monitor and improve the analytical performances of clinical laboratories. To guarantee suitable results also during the COVID-19 pandemic, EQA scheme providers have implemented specific schemes assessing different SARS-CoV-2 diagnostic systems. This study aims to describe the results collected in an experimental EQA scheme for molecular diagnostic of SARS-CoV-2 managed by INSTAND eV with the collaboration of the Centre of Biomedical Research for Quality in Laboratory Medicine for Veneto Region Laboratories. Methods: the qualitative EQA results collected in three surveys (two in 2020 and one in 2021) for 18 samples total, have been summarized to identify the percentage of laboratory results per sample. Control samples were provided by NationalesKonsiliarlaboratorium fur Coronaviren of Berlin. Results: even though the average of the participating laboratories strongly decreased between surveys, a good agreement was found among results (95% to 99.8%). A totally of 0.2% - 4% of incorrect results and 0% - 1.1% of indeterminate results were reported. In addition, the sequencing analysis and the point mutations analysis, included in the last analyzed survey, revealed a good agreement between participating laboratories with an overall score from 74.8% to 89.6% for the sequencing and from 90.65% to 95.33% for the point mutations, respectively. Conclusions: the EQA programs are a fundamental quality assurance tool to evaluate the laboratory performance and to appreciate the State-of-the-Art of the different diagnostic systems used by participating laboratories. The need for an EQA scheme for every test performed in the laboratory is mandatory to guarantee patient safety.
ABSTRACT
Background: External Quality Assessment (EQA) is a valuable tool to monitor and improve the analytical performances of clinical laboratories. During the COVID-19 pandemic, the number of kits to detect the infection and the number of tested samples intensified to satisfy the test request. To guarantee suitable results, EQA scheme providers have implemented specific schemes assessing different SARS-CoV-2 diagnostic systems. This study aims to describe the results collected in an experimental EQA scheme for molecular diagnostic of SARS-CoV-2 managed by INSTAND e.V with the collaboration of the Centre of Biomedical Research for Quality in Laboratory Medicine for Veneto Region Laboratories. Methods: The qualitative EQA results collected, two surveys in 2020 and one in 2021, for 18 samples total, have been summarized to identify the percentage of laboratory results per sample. Control samples included SARS-CoV-2 or other seasonal coronaviruses (MERSCoV, HCoV 229E, HCoV OC43) provided by Nationales Konsiliarlaboratorium fur Coronaviren of Berlin. SARSCoV-2 Variants of Concern (VOCs) were included only in the 2021 survey. Results: The average of the participating laboratories strongly decreased between the first survey of 2020 (927) and the last analysed survey, March 2021 (594). The main analytical procedures used, in the first, second and third survey respectively were CEPHAID kits (11.6%, 12% and 11.7%), in-house produced assays (10.4, 6.2 and 5%), SEEGENE kits (8.5%, 8.1% and 7.9%), ROCHE Diagnostics (8.3%, 8.5% and 6.9%) and ALTONA Diagnostics kits (6.1, 6.2 and 4.5%). A good agreement was found among laboratories results, with an overall range from 95% to 99.8%. Furthermore, generally from 0.2% to 2.9% of incorrect results and 0% to 1.1% of indeterminate results were reported. Conclusions: The EQA programs are a fundamental quality assurance tool to evaluate the laboratory performance and know the State-of-the-Art diagnostic systems used by participating laboratories. The need for an EQA scheme for every test performed in the laboratory is mandatory to guarantee patient safety.