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
Introduction: since the scarce diagnostic accuracy of specific circulating antibodies for SARS-CoV-2, we aimed to assess the clinical utility of IgM detection in SARS-CoV-2 using the Big Data analysis. Methods: this is a retrospective study;all the blood samples collected between March and September 2020 were processed using a lateral flow immunoassay (LFIA) kit for IgG and IgM antybody testing. Positives results were tested again using a chemiluminescent method. Subjects confirmed with a positive result were contacted for a molecular test. Results: more than 69 000 serological tests (from 42 911 subjects) were performed. 94.5% (40 559/42 911) of subjects had negative results for both IgG and IgM. 1.5% (n = 640) subjects had both IgG and IgM positive results, and viral RNA research confirmed positivity in 16% (85/533). Among subjects with IgG negative and IgM positive results (n=271), a positivity was confirmed in 1% (4/270). Conversely, in subjects with IgG positive and IgM negative results, a positivity was confirmed in 8% (97/1 215). Therefore, the analysis suggests that up to 98% of serological test results of IgM positivity and IgG negativity are false positive. Discussion: the study, based on Big Data analysis application, proved the scarce clinical utility of IgM detection in COVID-19 management, and underlines the responsibility of laboratory professionals in highlighting the limitations of the serological tests also due to uncertainty in their interpretation.
ABSTRACT
Professional societies in many countries have developed ethics policies and guidance materials for laboratory medicine which, just like any other area of medicine, must adhere to high ethical standards in order to assure quality and safety in health care. In particular, the International Organization for Standardization (ISO) in the accreditation standard ISO 15189:2012 "Medical laboratories − Requirements for quality and competence" has dedicated a specific section to this issue. However, the COVID-19 pandemic has raised the awareness of the urgent need to reassess and update ethical codes, and has highlighted current challenges and critical issues, such as access to diagnostics and laboratory testing, the value of laboratory information and the need for well-integrated diagnostic information. In the present paper, proposals are made for the updating of ethical codes currently required in laboratory medicine.
ABSTRACT
The coronavirus disease 19 (COVID-19) pandemic is a major challenge for all healthcare systems, as well as for social stability and the economy. The clinical spectrum of COVID-19 is: asymptomatic;mild to moderate;severe;and critical disease, leading to different fatality rates. Although countless studies have been published to better understand the pathophysiology of this infectious disease, the mecha-nisms of action of the virus, and the immunological respons-es, further research is needed to unravel the precise host factors determining COVID-19 susceptibility and severity. A considerable interest from the media and the general public has focused on the disproportionately high COVID-19-re-lated mortality in men. This sex discrepancy may be attrib-uted to biological, genetic and lifestyle differences between males and females, since sex is one of the variables affecting innate and adaptive immune responses, resulting in sex-specific outcomes in patients with infectious and autoim-mune disorders. Therefore, in this paper we will review the available data on sex-and gender-related differences in COVID-19 susceptibility and severity. © 2022, Il Pensiero Scientifico Editore s.r.l.. All rights reserved.
ABSTRACT
Background: Understanding the long-term kinetics of the immune response against SARS-CoV-2 infection is crucial in guiding public health policies and optimizing of vaccination strategies. While it is known that SARS-CoV-2 specific antibodies may persist in adults 12 months after infection, data are lacking in the pediatric population. We herein describe the long-term immune response in children following SARS-CoV-2 infection. Methods: Single-centre, prospective observational study analyzing family clusters of COVID-19 attending the Pediatric Department, University of Padua (Italy). Confirmed COVID-19 infection was defined by positive SARS-CoV-2 PCR and/or IgG serology. All patients with confirmed infection at enrolment underwent serological follow-up at 1-4, 5-10, and >10 months after infection. Plasma was analyzed to quantify anti-SARS-CoV-2 S-RBD IgG, by chemiluminescent immunoassay, performed on MAGLUMI™2000 Plus (Snibe Diagnostics). IgG title >4.3 kBAU/L was considered positive. Results: Among 902 subjects (252 COVID-19 family clusters), 698 had confirmed COVID-19, including 352 children/older siblings aged 8.6 ±5.1 years, and 346 parents aged 42.5 ±7.1 years;of those, 96.5% cases had asymptomatic/mild COVID-19. Children showed significantly higher S-RBD IgG titers than older subjects across all follow-up time points, with an overall mean S-RBD IgG titer <3 years of age five-fold higher than adults (282.3 [139-516.6] kBAU/L vs 56.7 [24.6-136.9] kBAU/L, p<0.001) (Table). The longitudinal analysis of 60 subjects sampled at least twice during follow-up demonstrated the persistence of antibodies up to 10 months from infection in all age classes. Subjects >6 years of age showed a significant progressive decline of the S-RBD IgG titer from the first serological follow-up. While, in younger children antibodies remained stable at 5-10 months of follow-up (p=0.0625), with a subsequent significant decline afterwards (p<0.001). Conclusion: In our unique family cluster cohort, we confirmed the different kinetics of the COVID-19 humoral response across several age groups of asymptomatic/mild COVID-19 cases in our family-cluster cohort. Children presented with higher S-RBD IgG titer at every time point up to 10 months of follow-up. Children less than 3 years demonstrated a more intense long-term resilience of their immune response, which started to decline significantly only after ten months from infection.
ABSTRACT
Background: Serological tests identifying SARS-CoV-2 IgG and IgM in serum play an important role in understanding the disease epidemiology. However, their immunological significance are currently undefined. There are many methods available for the detection of specific Abs whit suboptimal diagnostic accuracy and relatively high throughput capacity and less stringent specimen requirements compared to RNA-based assays. We aimed to assess the clinical utility of IgM detection in SARSCoV- 2 using the big data analysis. Methods: We conduct a retrospective study analyzing with a big data analysis all samples collected between 11 March and 30 September 2020. All serum samples received at the laboratory were processed using qualitative and commercially available rapid lateral flow immunoassay tests for 2019-nCoV IgG and IgM. Positive results were confirmed using a chemiluminescent method. Subjects with a positive result were contacted from the Department of Public Health for further tests (viral RNA research or subsequent serological tests) for definitive diagnosis.Results: A total of 69,343 serological tests (in 42,911 subjects) and 140,065 oropharyngeal or nasopharyngeal swabs (in 88,771 subjects) were performed. 94.5% of subjects screened (n=40,559) had negative results for both IgG and IgM. Of the 640 subjects with both IgG and IgM positive results, viral RNA research confirmed positivity in 16%. Of the subjects with IgG negative and IgM positive results, a positivity was confirmed in 1.4% (n=7/478) subjects. Subsequent serological testing confirmed IgG positivity in 8 subjects (1.6%). Conversely, in subjects with IgG positive and IgM negative results, a positivity was confirmed in 7.9%. Therefore, analysis suggests that up to 94% of serological test results of IgM positivity and IgG negativity are false positive whereas, serological test results of IgG positive and IgM negative are confirmed true positives in around 7.9% of subjects. Discussion: Our study, based on big data analysis application, confirms the scarce clinical utility of IgM anti SARS-CoV-2 detection in COVID-19 management, and underlines the responsibility of laboratory medicine professionals to highlight limitations of the SARS-CoV-2 serological tests due to uncertainty in their interpretation.
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.
ABSTRACT
Background and Aim: Salivary SARS-CoV-2 Ab determination could be suitable for monitoring the viral spread and vaccination efficacy, especially in pediatric patients. We investigated N/S1-RBD IgG antibody levels in salivary samples of infectious-naïve vaccinated subjects and of COVID-19 patients, further comparing levels with serum anti-SARS-CoV-2 S-RBD IgG. Methods: A total of 72 subjects were enrolled at the Padova University Hospital: 36 COVID-19 patients and 36 health care workers (HCW), who underwent a complete vaccination campaign with BNT162b2 (BioNTech/Pfizer). All collected a salivary sample, using Salivette (Sarstedt, Nümbrecht Germany). For 9 HCW, salivary samples were collected at three different times within the same day (before breakfast, at 10 am, and after lunch). A serum sample was also collected for all individuals. Time post symptoms onset or time from the first vaccine were also recorded. Salivary COVID-19 N/S1 RBD (sal-IgG) ELISA (RayBiotech, GA, USA) and anti-SARS-CoV-2 S-RBD IgG Ab (ser-IgG) (Snibe Diagnostics, Shenzhen, China) were used for determining IgG Ab. Results: Subjects' mean age (±sd) was 35.8±18.2 yrs. Age significantly differed (p<0.001) from COVID-19 patients [29.7±17.3 yrs] and HCW [47.1±12.9 yrs]. Positive sal-IgG were found in 70/72 (97.2%) samples;in sera, 71/72 (98.6%) samples were positive to ser-IgG. The sal-IgG median levels differed from COVID-19 to vaccinated HCW, being in salivary samples 0.21 kAU/L and 0.8 kAU/L (p =0.030), respectively;median levels for ser-IgG in COVID-19 and vaccinated HCW were 135 kBAU/L and 940 kBAU/L, respectively (p<0.001). Salivary IgG levels were not influenced by time post-symptom onset or time post-vaccination, both on vaccinated HCW (rho= -0.147, p=0.402) and COVID-19 subjects (rho=0.0267, p=0.986). Ser-IgG levels was not influenced by the time post-symptom onset for COVID-19 subjects (rho=0.102, p=0.419), while a strong significant correlation was found with time post-vaccination in HCW (rho=-0.6292, p<0.001). Sal-IgG levels were notinfluenced by the daytime of collection (rho=0.148, p=0.373). Passing-Bablok regressions showed that sar- IgG and ser-IgG comparability was assessable only when ser-IgG values were divided by 1000, being slope and intercept 0.068 (95%CI: 0.069-0.341) and 0.221 (95%CI:- 0.097 to 0.786), respectively. Conclusions: Salivary IgG is efficiently detectable both in COVID-19 and in vaccinated individuals and analyses appeared to be not influenced by the daytime of collection. The analyses performed showed that, overall, sal-IgG were lower than ser-IgG, and thus comparability with serum levels needs to be better explored.
ABSTRACT
Background. One of the strategies suggested for the containment of SARS-CoV-2 pandemic is testing at risk populations with rapid turn-out of results, contact tracing and isolation of infected individuals, at least until vaccination programs have been completed. Molecular testing of naso-pharyngeal swabs (NPS) is considered gold-standard, but antigenic testing should offer the advantage of being more rapid. Aim. The aim of this study was to evaluate the clinical performance of two chemiluminescent immunoassays on laboratory automated platforms, LIAISON® SARS-CoV-2 Ag Assay (DiaSorin) and Elecsys SARS-CoV-2 Antigen (Roche), to detect SARS-CoV-2 N antigen in NPS. Patients and Methods. A total of 281 subjects were consecutively enrolled (116 M, 165 F) from three different cohorts: 14 were COVID-19 in-patients (Group 1), 149 were patients enrolled at the emergency unit (Group 2) while 118 were healthcare employees under SARS-CoV-2 periodic surveillance (Group 3). All subjects underwent NPS with eSwab Copan. Antigen and molecular testing were performed soon after collection. Results. Thirty subjects were SARS-CoV-2 positive at molecular testing. Liaison antigen was positive (>200 TCID50/ml) in 22/30 (Se=73.3%), equivocal (100-200 TCID50/ml) in 4/30 and negative (<100 TCID50/ml) in 4/30 subjects. Specificity was 61.8% since 60/157 negative samples had equivocal results. With Elecsys sensitivity was 75.9% and specificity 99.5%. ROC curves were performed to compare the two assays and to identify the best cut-off. The areas under the curves were not different (η2=0.14;Prob>η2=0.7077). The highest likelihood ratio for Liaison corresponded to 150 TCID50ml cut-off, while for Elecsys to 1 index value. With these thresholds sensitivity of these two assays were 86% and 87% respectively, with 99% specificity. The limitations in sensitivity were due to false negative results for samples with Ct values at molecular analysis higher than 25. No false negative case was recorded among those with Ct lower than 25. Conclusions. In conclusion NPS SARS-CoV-2 antigen testing with chemiluminescent immunoassays allows the rapid detection of positive samples with a sensitivity and specificity that meet the recommendations of the WHO for this type of testing.
ABSTRACT
Background: The approach to diagnosing, treating and monitoring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection relies strongly on laboratory resources, with serological testing representing the mainstay for studying the onset, nature and persistence of humoral immune response. This study was aimed at evaluating the analytical performance of the novel Beckman Coulter anti-SARS-CoV-2 immunoglobulins G (IgG) chemiluminescent immunoassay. Methods: This analytical assessment encompassed the calculation of intra-assay, inter-assay and total imprecision, linearity, limit of blank (LOB), limit of detection (LOD), functional sensitivity, and comparison of anti-SARS-CoV-2 antibodies values obtained on paired serum samples using DiaSorin Liaison SARS-CoV-2 S1/S2 IgG and Roche Elecsys Anti-SARS-CoV-2 total antibodies. Diagnostic performance was also tested against results of molecular testing on nasopharyngeal swabs, collected over the previous 4 months. Results: Intra-assay, inter-assay and total imprecision of Beckman Coulter anti-SARS-CoV-2 IgG were between 4.3-4.8%, 2.3-3.9% and 4.9-6.2%, respectively. The linearity of the assay was excellent between 0.11-18.8 antibody titers. The LOB, LOD and functional sensitivity were 0.02, 0.02 and 0.05, respectively. The diagnostic accuracy (area under the curve;AUC) of Beckman Coulter anti-SARS-CoV-2 IgG compared to molecular testing was 0.87 (95% CI, 0.84-0.91;P<0.001) using manufacturer's cut-off, and increased to 0.90 (95% CI, 0.86-0.94;P<0.001) with antibody titers. The AUC was non-significantly different from that of Roche Elecsys Anti-SARS-CoV-2, but was always higher than that of DiaSorin Liaison SARS-CoV-2 S1/S2 IgG. The correlation of Beckman Coulter Access SARS-CoV-2 IgG was 0.80 (95% CI, 0.75-0.84;P<0.001) with Roche Elecsys Anti-SARS-CoV-2 and 0.72 (95% CI, 0.66-0.77;P<0.001) with DiaSorin Liaison SARS-CoV-2 S1/S2 IgG, respectively. Conclusions: The results of this analytical evaluation of Beckman Coulter Access anti-SARS-CoV-2 IgG suggests that this fully-automated chemiluminescent immunoassay represents a valuable resource for large and accurate seroprevalence surveys. © Journal of Laboratory and Precision Medicine. All rights reserved.
ABSTRACT
Introduction: D-Dimer assessment represents a cornerstone in the diagnostic approach to several thrombotic disorders. Recent literature has highlighted the role of D-Dimer also in the diagnostic pathway of coronavirus infection (COVID-19) and the importance of harmonized reporting [D-dimer unit (DDU) or fibrinogen equivalent unit (FEU);unit of measure;cut-off] in order to guarantee the correct interpretation of the results. Methods: D-Dimer data from 100 EQA participants and the inter-laboratory variability (CV%) of the last 7 years for the most used analytical systems: Werfen, HemosIL HS;Werfen, HemosIL HS-500;Auto D-D, Sclavo;Innovance, Siemens;VIDAS, bioMérieux and STA Liatest, Stago have been evaluated. Results: Concerning the results expression in DDU or FEU, we observed a prevalence of FEU (55.1%) over DDU (44.9%);the value was confirmed in the last 7 years (average FEU = 55.6%), differently from data obtained in the survey conducted in 2014 at a national level. The units used are: ng/mL (67.8%), μg/L (29.0%) and mg/L (3.2%) for D-Dimer DDU;ng/mL (57.9%), μg/mL (21.0%), μg/L (15.8%) and mg/L (5.3%) for D-Dimer FEU. Inter-laboratory variability (mean CV%) calculated on a total of 72 controls is lower for all diagnostic systems at pathological levels than the one observed for concentrations below the cut-off. Discussion: This study demonstrates that the reporting of D-Dimer results does not comply with the 2014 SIBioC consensus document which recommended the use of μg/L FEU, and highlights 8 different types of information. Data reported in this study call for the harmonization of D-Dimer reporting in order to guarantee the correct interpretation of the information, both in the case of COVID-19 and in all the diseases already known where this analyte has a clinical relevance.
ABSTRACT
The recent pandemic outbreak caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and associated with the pathology called COVID-19 (coronavirus disease 2019), has now become one of the most strenuous health care challenges since the emergence of the three pandemics caused by influenza viruses during the past century. Throughout the clinical decision-making of COVID-19, laboratory tests are essential for supporting the screening, diagnosis, prognostication and therapeutic monitoring of this severe infectious disease. Serological testing, that reflects the humoral immune response developing after interaction between the host and the virus (or its components), enables to garner a vast array of clinical information which can be especially used in seroprevalence or seroconversion studies. To this end, the Task Force on COVID-19 of the Italian Society of Clinical Biochemistry and Clinical Molecular Biology (SIBioC) has endorsed a series of technical, practical and clinical ad interim recommendations, aimed at facilitating and optimizing the introduction, clinical usage and governance of SARS-CoV-2 serological immunoassays in routine practice.
ABSTRACT
With the ongoing coronavirus disease 2019 (COVID-19) pandemic outbreak spreading all around the world, an extensive vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now universally regarded as one of the most effective strategies for counteracting the unremittent spread of this novel coronavirus. Nonetheless, the reasonable need to identify segments of the population in which vaccination shall be prioritized for avoiding a possible shortage of vaccines seems to collide with indications provided by many national and international healthcare organizations, that endorse widespread vaccination irrespective of a positive history of prior symptomatic or asymptomatic SARS-CoV-2 infection. To this end, this document provides an ad interim guidance aimed at prioritizing SARS-CoV-2 vaccination in people who are more likely to be infected, re-infected and/or to develop more aggressive COVID-19 illness, essentially based on routine assessment and monitoring of anti-SARS-CoV-2 immune response.
ABSTRACT
The COVID-19 pandemic has affected all aspects of society, dramatically changing our day-to-day lives and habits. It has also changed clinical practice, including practices of clinical laboratories. This pandemic, in fact, led to an impressive increase of the visibility and value of clinical laboratories to the population at large. The key role of laboratory testing inmodernmedicine requires laboratory professionals to take on more, ever new responsibility with the aim of improving not only analytical performance but appropriate requesting and utilization of laboratory tests, as well as the integration of laboratory information with all other diagnostic and clinical data. Laboratory testing is needed for the right diagnosis even in asymptomatic/ presymptomatic subjects using bothmolecular and antigen-based tests, for the appropriatemonitoring and prognostication of disease severity by using biochemical, coagulation, hematological tests and for epidemiological surveillance. In addition, laboratory testing particularly serological assays to measure SARS-CoV-2 specific antibodies play a key role in evaluating the efficacy of vaccines already developed and under development. In real life, antibody testing should be used to develop prioritization strategies, to reduce unnecessary potential side-effects in those people who have already developed the disease and to better evaluate the immune response particularly in immunosuppressed patients and patients under therapies. Finally, an increasing interest is to integration of serological data with cell-mediated immunoresponses.
ABSTRACT
Background: Serology could help defining the real extent of Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV2) diffusion in the population, especially in individuals considered at higher risk of SARS-CoV2 infection (COVID-19), such as Spondiloarthritis (SpA) patients undergoing immunosuppressive therapy or health care workers (HCW). In fact, COVID-19 detection is complicated by the fact that many patients can be asymptomatic. In these cases, it has also been suggested that a weaker immune response might be elicited. In this context, the role of anti-cytokine targeted therapy -commonly used as treatment in SpA-is uncertain, as it is not clear whether it is detrimental or protective towards severe disease forms. Objectives: The aim of the study was to explore the potential role of serology in detecting previous contact with SARS-CoV2 in SpA patients and HCW, and compare the frequency of positive findings with a control population. Methods: Consecutive patients affected by axial or peripheral SpA, classified according to Assessment of SpondyloArthritis international Society (ASAS) criteria and undergoing cytokine-targeted therapy, as well as HCW and controls from the pre-COVID-19 era (control group, 2015) were recruited. In SpA patients, disease activity was assessed by Ankylosing Spondylitis Disease Activity Score (ASDAS) and Disease Activity Score on 28-joint-count (DAS28). Sera from all patients were analysed through chemiluminescent analytical system (CLIA) for the presence of IgG and IgM anti-SARS-CoV2. Patients with a positive serological test (either IgM or IgG) additionally underwent real time Polymerase Chain Reaction (RT-PCR) in nasopharyngeal swabs in order to test for active infection. In SpA patients, serology was repeated after 3 months. Data across the 3 groups were compared by ANOVA or Chi-square, while comparison between 2 groups were conducted by Wilcoxon signed rank test or Chi-Square, for continuous and categorical data respectively. P ≤ 0.05 were considered as significant. Results: A total of 396 patients were recruited: 200 SpA, 95 HCW and 101 healthy controls. SpA patients were mostly (54%) males, with mean age 49.6 ±14.7 years, and all were treated with anti-TNFα (78%), anti-IL-17 (9%) and anti-IL-23 drugs (7%), or small molecules (6%). Their disease activity level was moderate-low as assessed by ASDAS (1.95 ±0.98) and DAS28 (2.33 ±2.02). Among HCW and controls, 35% and 62% were male, with mean age 46.7 ±12.9 and 50.6±10.6 respectively. Positive serology (IgM or IgG, or both) was found in 12.5% SpA patients, 8.4% HCW, 0% controls (p=0.001). Among these, IgM titres were higher in the SpA group than in HCW (2.76±2.94 versus 0.80±0.67 KU/L, p= 0.016), while IgG mean titres were lower in the SpA group than in HCW (0.88±3.18 KU/L versus 1.05±0.88, p= 0.035). SpA patients with positive serology more frequently reported COVID-19 like symptoms than those with negative serology (20% vs 4%, p=0.009) and 2 had COVID-19 as confirmed by RT-PCR, none with a severe disease course. None of the HCW reported symptoms or tested positive by RT-PCR. In the SpA patients, at 3 months, the mean IgM titre decreased from 2.76±2.93 to 2.38±2.95 (p=0.001), while the IgG titres decreased from 0.89±3.25 to 0.31±0.87 (p=ns). Interestingly, the IgM or IgG titer at a single-patient level did not seem to change much in terms of absolute value (Figure 1), except in one patient, with documented COVID-19 (positive RT-PCR), in whom IgG level even decreased at 3 months. Conclusion: Serology revealed that exposure to COVID-19 in SpA patients, as well as HCW, was higher than expected based on reported symptoms. Targeted anti-cytokine therapy could act as a protective factor for a severe disease course in SpA patients. However, in this population, IgG and IgM titres did not change in a clinically significant manner at 3 months, and patient did not seem to develop an immune profile consistent with durable response. This result could be due to a weaker immune response in mild infections, but further studies are w rranted to clarify the pathophysiology beyond these observations.