Improved Performance of the QuantiFERON-SARS-CoV-2 Assay with the Extended Set.

Multiple assays have been developed for the characterization of the functional activation of SARS-CoV-2 specific T-cells. This study was conducted to assess the post-vaccination and post-infection T cell response, as detected by the QuantiFERON-SARS-CoV-2 assay using the combination of three SARS-CoV-2 specific antigens (Ag1, Ag2 and Ag3). An amount of 75 participants with different infection and vaccination backgrounds were recruited for the evaluation of humoral and cellular immune responses. An elevated IFN-γ response in at least one Ag tube was observed in 69.2% of convalescent subjects and 63.9% of vaccinated ones. Interestingly, in a healthy unvaccinated case and three convalescents with negative IgG-RBD, we detected a positive QuantiFERON test after stimulation with Ag3. The majority of the T cell responders reacted simultaneously to the three SARS-CoV-2 specific antigens, and Ag3 demonstrated the highest rate of reactivity. At univariable analysis, the only factor that was associated with an absence of a cellular response was time from blood collection, being less than 30 days (OR:3.5, CI95% [1.15-10.50], p = 0.028). Overall, the inclusion of Ag3 improved the performance of the QuantiFERON-SARS-CoV-2 and showed a particular interest among subjects who fail to achieve a measurable antibody response after infection or vaccination.

T Lymphocyte Subset Counts and Interferon-Gamma Production in Adults and Children with COVID-19: A Narrative Review.

Adults and children exhibit a broad range of clinical outcomes from SARS-CoV-2 infection, with minimal to mild symptoms, especially in the pediatric age. However, some children present with a severe hyperinflammatory post-infectious complication named multisystem inflammatory syndrome in children (MIS-C), mainly affecting previously healthy subjects. Understanding these differences is still an ongoing challenge, that can lead to new therapeutic strategies and avoid unfavorable outcomes. In this review, we discuss the different roles of T lymphocyte subsets and interferon-γ (IFN-γ) in the immune responses of adults and children. Lymphopenia can influence these responses and represent a good predictor for the outcome, as reported by most authors. The increased IFN-γ response exhibited by children could be the starting point for the activation of a broad response that leads to MIS-C, with a significantly higher risk than in adults, although a single IFN signature has not been identified. Multicenter studies with large cohorts in both age groups are still needed to study SARS-CoV-2 pathogenesis with new tools and to understand how is possible to better modulate immune responses.

Evaluation of T cell responses with the QuantiFERON SARS-CoV-2 assay in individuals with 3 doses of BNT162b2 vaccine, SARS-CoV-2 infection, or hybrid immunity.

Cellular immunity after SARS-CoV-2 infection or immunization may be important for long-lasting protection against severe COVID-19 disease. We investigated cellular immune responses after SARS-CoV-2 infection and/or vaccination with an interferon-γ release assay (QuantiFERON, QFN), in parallel, with humoral immunity assessment. We recruited 41 participants: unvaccinated convalescent children and adults and vaccinated uninfected or vaccinated convalescent adults. All vaccinated adults had received three doses of the BNT162b2 COVID-19 vaccine at 6.2 to 10.9 months prior to their inclusion to the study. All the unvaccinated participants were tested negative with QFN. Regarding the vaccinated population, 50% (8/16) of the vaccinated uninfected adults and 57.1% (8/14) of the vaccinated convalescent adults were tested positive. QFN did not detect T cell responses in unvaccinated individuals and in a significant number of vaccinated individuals. Further comparative studies with different immunoassays are required to elucidate whether this is the result of waning immunity or low sensitivity of the assay.

Prevalence of Latent Tuberculosis Infection among Patients Undergoing Regular Hemodialysis in Disenfranchised Communities: A Multicenter Study during COVID-19 Pandemic.

Background and Objectives: Due to their weakened immune response, hemodialysis (HD) patients with latent tuberculosis infection (LTBI) are at higher risk for active tuberculosis (TB) disease and are more subject to patient-to-patient transmission within dialysis units. Consequently, current guidelines advocate screening these patients for LTBI. To our knowledge, the epidemiology of LTBI in HD patients has never been examined before in Lebanon. In this context, this study aimed to determine LTBI prevalence among patients undergoing regular HD in Northern Lebanon and to identify potential factors associated with this infection. Notably, the study was conducted during the COVID-19 pandemic, which is likely to have catastrophic effects on TB and increase the risk of mortality and hospitalization in HD patients. Materials and Methods: A multicenter cross-sectional study was carried out in three hospital dialysis units in Tripoli, North Lebanon. Blood samples and sociodemographic and clinical data were collected from 93 HD patients. To screen for LTBI, all patient samples underwent the fourth-generation QuantiFERON-TB Gold Plus assay (QFT-Plus). Multivariable logistic regression analysis was used to identify the predictors of LTBI status in HD patients. Results: Overall, 51 men and 42 women were enrolled. The mean age of the study population was 58.3 ± 12.4 years. Nine HD patients had indeterminate QFT-Plus results and were therefore excluded from subsequent statistical analysis. Among the remaining 84 participants with valid results, QFT-Plus was positive in 16 patients, showing a positivity prevalence of 19% (95% interval for p: 11.3%, 29.1%). Multivariable logistic regression analysis showed that LTBI was significantly associated with age [OR = 1.06; 95% CI = 1.01 to 1.13; p = 0.03] and a low-income level [OR = 9.29; 95% CI = 1.62 to 178; p = 0.04]. Conclusion: LTBI was found to be prevalent in one in five HD patients examined in our study. Therefore, effective TB control measures need to be implemented in this vulnerable population, with special attention to elderly patients with low socioeconomic status.

Evaluation of QuantiFERON SARS-CoV-2 interferon-γ release assay following SARS-CoV-2 infection and vaccination.

T cells are important in preventing severe disease from SARS-CoV-2, but scalable and field-adaptable alternatives to expert T-cell assays are needed. The interferon-gamma release assay QuantiFERON platform was developed to detect T-cell responses to SARS-CoV-2 from whole blood with relatively basic equipment and flexibility of processing timelines. Forty-eight participants with different infection and vaccination backgrounds were recruited. Whole blood samples were analysed using the QuantiFERON SARS-CoV-2 assay in parallel with the well-established 'Protective Immunity from T Cells in Healthcare workers' (PITCH) ELISpot, which can evaluate spike-specific T-cell responses. The primary aims of this cross-sectional observational cohort study were to establish if the QuantiFERON SARS-Co-V-2 assay could discern differences between specified groups and to assess the sensitivity of the assay compared with the PITCH ELISpot. The QuantiFERON SARS-CoV-2 distinguished acutely infected individuals (12-21 days post positive PCR) from naïve individuals (P < 0.0001) with 100% sensitivity and specificity for SARS-CoV-2 T cells, whilst the PITCH ELISpot had reduced sensitivity (62.5%) for the acute infection group. Sensitivity with QuantiFERON for previous infection was 12.5% (172-444 days post positive test) and was inferior to the PITCH ELISpot (75%). Although the QuantiFERON assay could discern differences between unvaccinated and vaccinated individuals (55-166 days since second vaccination), the latter also had reduced sensitivity (44.4%) compared to the PITCH ELISpot (66.6%). The QuantiFERON SARS-CoV-2 assay showed potential as a T- cell evaluation tool soon after SARS-CoV-2 infection but has lower sensitivity for use in reliable evaluation of vaccination or more distant infection.

Performance of an interferon-γ release assay-based test for cell-mediated immunity to SARS-CoV-2.

In search for immunological correlates of protection against acute coronavirus disease 2019 (COVID-19) there is a need for high through-put assays for cell-mediated immunity (CMI) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We established an interferon-γ release assay -based test for detection of CMI against SARS-CoV-2 spike (S) or nucleocapsid (NC) peptides. Blood samples obtained from 549 healthy or convalescent individuals were measured for interferon-γ (IFN-γ) production after peptide stimulation using a certified chemiluminescence immunoassay. Test performance was calculated applying cutoff values with the highest Youden indices in receiver-operating-characteristics curve analysis and compared to a commercially available serologic test. Potential confounders and clinical correlates were assessed for all test systems. 522 samples obtained from 378 convalescent in median 298 days after PCR-confirmed SARS-CoV-2 infection and 144 healthy control individuals were included in the final analysis. CMI testing had a sensitivity and specificity of up to 89% and 74% for S peptides and 89% and 91% for NC peptides, respectively. High white blood cell counts correlated negatively with IFN-γ responses but there was no CMI decay in samples obtained up to one year after recovery. Severe clinical symptoms at time of acute infection were associated with higher measures of adaptive immunity and reported hair loss at time of examination. This laboratory-developed test for CMI to SARS-CoV-2 NC peptides exhibits excellent test performance, is suitable for high through-put routine diagnostics, and should be evaluated for clinical outcome prediction in prospective pathogen re-exposure.

Immunogenicity of SARS-CoV-2 vaccination in adolescents with cardiac disease.

BACKGROUND: Although widely reported to affect older adults more, coronavirus disease 2019 (COVID-19) also affects adolescents, especially those with co-morbidities, including heart diseases. The safety and efficacy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines has been established in healthy adolescents, yet there are few data for humoral and cellular immunogenicity in adolescents with cardiac diseases. METHODS: We evaluated anti-spike antibodies, neutralizing activities, and interferon-gamma production prior to and after SARS-CoV-2 vaccination in adolescents with cardiac diseases and healthy controls. RESULTS: Five healthy adolescents and 26 patients with cardiac diseases, including congenital heart disease (CHD, n = 10), dilated cardiomyopathy (DCM, n = 4), idiopathic pulmonary arterial hypertension (IPAH, n = 4), and those post-heart transplantation (post-HTx, n = 8) were enrolled. No severe adverse events, including myocarditis and pericarditis, were noted, even in patients with severe heart failure. Febrile events were noted after 21 of 62 injections (34%). All the healthy adolescents and 21 of the 26 patients (81%) showed sufficient elevation of neutralizing antibodies after the second dose of vaccination. Neutralizing antibodies and cellular immunity were absent in four of the eight post-HTx patients and one with single ventricle CHD. There was no correlation between the anti-spike and neutralizing antibody titers and interferon-gamma levels. When comparing the clinical characteristics of the patients post-HTx who did or did not acquire antibodies, there was no significant difference in the immunosuppressant types and trough levels. CONCLUSIONS: SARS-CoV-2 mRNA vaccine has efficient immunogenicity for adolescents with CHD, IPAH, and DCM. Half of post-HTx patients could not acquire sufficient humoral immunity.

Accuracy of QuantiFERON SARS-CoV-2 research use only assay and characterization of the CD4+ and CD8+ T cell-SARS-CoV-2 response: comparison with a homemade interferon-γ release assay.

OBJECTIVES: In this study, we aimed to characterize the SARS-CoV-2-specific T cell response detected by the QuantiFERON SARS-CoV-2 research use only assay in terms of accuracy and T cell subsets involved compared with a homemade interferon (IFN)-γ release assay (IGRA). METHODS: We evaluated T cell response by the standardized QuantiFERON SARS-CoV-2 tubes (antigen [Ag]1 and Ag2) and a homemade IGRA quantifying IFN-γ response to SARS-CoV-2 spike peptides (homemade-IGRA-SPIKE test). We evaluated the T cell subsets mediating the specific response using flow cytometry. RESULTS: We prospectively enrolled 66 individuals: COVID-19 or post-COVID-19 subjects and NO-COVID-19-vaccinated subjects, including healthy donors and immunocompromised subjects. The standardized kit detected 62.1% (41/66) of T cell responders. Ag2 tube showed a higher IFN-γ quantitative and qualitative response. Ag1 tube response was mainly mediated by CD4+ T cells; Ag2 tube response was mediated by CD4+ and CD8+ T cells. The homemade-IGRA-SPIKE test detected a higher number of responders (52/66, 78.8%) than the QuantiFERON SARS-CoV-2 assay (P = 0.056). The response was found in both T cell subsets, although a higher magnitude and response rate was observed in the CD4+ T cell subset. CONCLUSION: The QuantiFERON SARS-CoV-2 response is mediated by CD4+ and CD8+ T cells. A lower number of responders is found compared with the homemade-IGRA-SPIKE test, likely because of the different peptide composition.

Prognostic Value of Mid-Region Proadrenomedullin and In Vitro Interferon Gamma Production for In-Hospital Mortality in Patients with COVID-19 Pneumonia and Respiratory Failure: An Observational Prospective Study.

Coagulopathy and immune dysregulation have been identified as important causes of adverse outcomes in coronavirus disease (COVID-19). Mid-region proadrenomedullin (MR-proADM) is associated with endothelial damage and has recently been proposed as a prognostic factor in COVID-19. In non-COVID-19 immunocompromised patients, low in vitro interferon gamma (IFNγ) production correlates with infection risk and mortality. This prospective, monocentric, observational study included adult patients consecutively admitted with radiologic evidence of COVID-19 pneumonia and respiratory failure. MR-proADM and in vitro IFNγ production were measured at T0 (day 1 from admission) and T1 (day 7 from enrollment). One hundred patients were enrolled. Thirty-six percent were females, median age 65 (Q1-Q3 54.5-75) years, and 58% had ≥1 comorbidity. Only 16 patients had received COVID-19 vaccination before hospitalization. At admission, the median PaO2:FiO2 ratio was 241 (157-309) mmHg. In-hospital mortality was 13%. MR-proADM levels differed significantly between deceased and survivors both at T0 (1.41 (1.12-1.77) nmol/L vs. 0.79 (0.63-1.03) nmol/L, p < 0.001) and T1 (1.67 (1.08-1.96) nmol/L vs. 0.66 (0.53-0.95) nmol/L, p < 0.001). In vitro IFNγ production at T0 and T1 did not vary between groups. When only the subset of non-vaccinated patients was considered, both biomarkers at T1 resulted significantly associated with in-hospital mortality. AUROC for MR-proADM at T0 to predict in-hospital mortality was 0.87 (95%CI 0.79-0.94), with the best cut-off point at 1.04 nmol/L (92% sensitivity, 75% specificity and 98% negative predictive value). In patients with COVID-19 pneumonia and different degrees of respiratory failure, MR-proADM at admission and during hospitalization resulted strongly associated with in-hospital mortality. Low in vitro IFNγ production after the first week of hospitalization was associated with mortality in non-vaccinated patients possibly identifying the subgroup characterized by a higher degree of immune suppression.

Changes in interferon-γ release assay readout after COVID-19 vaccination: A prospective cohort study.

OBJECTIVES: Interferon-γ release assays (IGRAs) are widely used in public health practice to diagnose latent tuberculosis. During the COVID-19 pandemic and rollout of COVID-19 vaccination, it has remained unclear whether COVID-19 vaccines interfere with IGRA readouts. METHODS: We prospectively recruited healthcare workers during their annual occupational health examinations in 2021. Baseline IGRA readouts were compared with follow-up data after the participants had received two doses of COVID-19 vaccination. RESULTS: A total of 134 baseline IGRA-negative cases (92 with ChAdOx1 vaccine, 27 with mRNA-1273 vaccine, and 15 with heterologous vaccination) and seven baseline IGRA-positive cases were analyzed. Among the baseline IGRA-negative cases, there were decreased interferon-γ concentrations over the Nil (P = 0.005) and increased Mitogen-Nil (P < 0.001) values after vaccination. For TB2-Nil value, a similar trend (P = 0.057) of increase was observed. Compared with the 0.35 IU/ml threshold, the baseline and follow-up readout differences were less than |± 0.10| IU/ml over the TB1-Nil and TB2-Nil values in >90% baseline IGRA-negative cases. No significant readout difference was observed among baseline IGRA-positive cases. CONCLUSION: COVID-19 vaccination did not change IGRA interpretation in most cases. Cases showing conversion/borderline IGRA readouts should be given special consideration.

The Pitfalls of Mining for QuantiFERON Gold in Severely Ill Patients With COVID-19.

Objective: To assess the proportion of indeterminate QuantiFERON-TB Gold Plus (QFT-Plus) results in patients admitted for severe coronavirus disease 2019 (COVID-19) pneumonia and evaluate the factors associated with indeterminate QFT-Plus results. Patients and Methods: Data on COVID-19 admissions at Mayo Clinic in Florida were extracted between October 13, 2020, and September 20, 2021, and data from a prepandemic cohort were extracted between October 13, 2018, and September 20, 2019. A secondary analysis of the COVID-19 cohort was performed using gradient boosting modeling to generate variable importance and SHapley Additive exPlanations plots. Results: Our findings demonstrated more indeterminate QFT-Plus test results in patients hospitalized for severe COVID-19 infection than in patients without COVID-19 (139 of 495, 28.1%). The factors associated with indeterminate QFT-Plus test results included elevated levels of C-reactive protein, ferritin, lactate dehydrogenase and interleukin-6 and included lower levels of leukocyte, lymphocyte, and platelet counts. Conclusion: The patients with severe COVID-19 had a higher likelihood of indeterminate QFT-Plus results, which were associated with elevated levels of inflammatory markers consistent with severe infection. Interferon-gamma release assay screening tests are likely confounded by COVID-19 infection itself, limiting the screening ability for latent tuberculosis infection reactivation. Indeterminate QFT-Plus results may also require follow-up QFT-Plus testing after patient recovery from COVID-19, increasing the cost and complexity of medical decision making and management. Additional risk assessments may be needed in this patient population for screening for latent tuberculosis infection in patients with severe COVID-19.

Prevalence of latent tuberculosis infection among pre-clinical and clinical medical students using QuantiFERON-TB gold plus and tuberculin skin test at a teaching hospital in Thailand: A cross-sectional study.

BACKGROUND: Healthcare workers are considered to be at a higher risk of acquiring tuberculosis (TB) infection than the general population. Clinical medical students are part of the healthcare team and clinical practice are done during their clinical rotation. They could be exposed to similar occupational risks as the healthcare workers. Most students who become infected have latent tuberculosis infection (LTBI) and may not exhibit any clinical symptoms. Some students with LTBI can progress to TB disease during clinical rotations in the hospitals. Therefore, screening for LTBI in this population represents hospital aspect of public health strategy and infection control in medical school in high TB burden countries. OBJECTIVE: We aimed to determine the prevalence of LTBI among fourth-year medical students and sixth-year medical students by using QuantiFERON-TB Gold Plus (QFT-Plus) and Tuberculin Skin Test (TST). METHODS: A cross-sectional study of fourth-year medical students (n = 73) and sixth-year medical students (n = 85) was conducted at the School of Medicine, Chulalongkorn University, Bangkok, Thailand. The medical students (n = 158) who met the eligibility criteria were recruited into the study. LTBI was detected by using QFT-Plus and some of the participants had a tuberculin skin test (TST). The TST was interpreted after 48-72 h. The participants who tested positive by QFT-Plus were considered to have LTBI. Demographic information and data on occupational TB exposure were collected via a questionnaire. A multivariate logistic regression was used to test for associations between independent variables and results of the QFT-Plus. RESULTS: A total of 158 participants were included in this study. The overall prevalence of LTBI was 6.3% (n = 10) as determined by QFT-Plus. The LTBI prevalence was higher in the sixth-year medical students (9.4%) compared to the fourth-year medical students (2.7%). Higher risk of LTBI was associated with sixth-year medical students (odds ratio, 3.69 [95%CI, 0.75-17.96]), but this was not significant. Moreover, history of occupational TB exposure without PPE yielded an odds ratio of 2.98 [95%CI, 0.68-13.12] but it was not statistically significant due to the small sample size. One hundred thirty-nine (88%) participants were BCG vaccinated as per the national vaccination requirements. No abnormal chest X-rays were found for any of the positive participants. Of the 158 participants, 41 (25.9%) of them had TST. Of the 41 participants, 6 (14.6%) tested positive at a cut-off of ≥ 10 mm for TST, which was concordant with QFT-Plus results. The agreement between the two tests was 0.57 using kappa coefficients. CONCLUSION: The screening of TB infection in new healthcare workers (HCWs), especially medical students, is essential to reduce future nosocomial TB incidences in the hospitals. This study showed that there was a high prevalence of LTBI among sixth-year medical students compared to fourth-year medical students. Our results suggest that tendency of higher LTBI prevalence might be associated with advanced clinical years, thus tailored public health education strategy and infection control in tertiary care hospitals for new healthcare workers in TB endemic countries may prevent nosocomial TB disease from developing in the future. Therefore, active surveillance should be done for all new HCWs, and TB preventive therapy should be administered to recent converters.

Analysis of high-resolution computed tomography chest in interferon gamma release assay negative COVID-19 patients: From a COVID hospital of Odisha, India

Background: Atypical category of COVID-19 could not be differentiated from tuberculosis (TB) in high-resolution computed tomography (HRCT) of the chest because of similar imaging features. This study aims to distinguish between the HRCT features of TB and atypical COVID-19. Methodology: Interferon-gamma release assay (IGRA) was performed in all the 54 COVID-positive patients, showing atypical COVID features that are suspicious of TB on the HRCT chest. Atypical imaging features such as a tree in bud nodules, patchy consolidations, cavitation with surrounding consolidation, discrete nodules, mediastinal lymphadenopathy, and pleural effusion were analyzed in 50 IGRA-negative patients. Results: We found trees in bud nodules (93%) and consolidations (56%) involving predominantly lower lobes, i.e., superior and posterobasal segments. Discrete nodules and cavitation with surrounding consolidation were seen involving predominantly upper lobes (78 and 57% cases, respectively), i.e., apicoposterior and lingular segments of the left upper lobe. The maximum number (67%) of right paratracheal enlarged nodes and bilateral pleural effusions (71%) were found in IGRA-negative COVID-19 patients. Conclusions: It is not always possible to differentiate features of atypical COVID-19 from TB based on HRCT chest alone because of similar appearances and distribution of tree in bud nodules, consolidation, cavitation, and lymphadenopathy in HRCT chest. Since both bilateral and unilateral pleural effusions may be seen in TB, it is impossible to differentiate COVID-19 from TB based on pleural effusion. Therefore, exclusion of TB will need supportive, relevant laboratory investigations (Sputum acid fast bacilli, cartridge-based nucleic acid amplification test, and IGRA) for appropriate diagnosis and management.

Indeterminate mycobacterium tuberculosis QuantiFERON post Moderna mRNA Covid-19 vaccination.

We report an interesting case of an indeterminate MTB QuantiFERON for a 26-year-old healthy soldier planned for a routine field exercise to Brunei. Further medical history revealed that the patient had a Moderna mRNA Covid-19 vaccine the day before his MTB QuantiFERON test. The patient was subsequently asked to repeat a T-spot test which was non-reactive, there were no longer any issues with the positive control for the T-spot test. Current Covid-19 research suggests that infection causes a dysregulation of the immune system, perhaps this might also be extrapolated where a Covid-19 vaccine might provoke an immune response which might interfere with some immunological assays. In summary there should be more research invested into the immunological interactions that the newly developed Covid-19 vaccinations have with our existing immunological tests such as QuantiFERON tests which forms a key cornerstone in our fight against tuberculosis.

Not Only COVID-19: Prevalence and Management of Latent Mycobacterium Tuberculosis Infection in Three Penitentiary Facilities in Southern Italy.

Latent Mycobacterium tuberculosis infection (LTBI) and active tuberculosis in prisoners are higher than the general population and are two public health concerns, especially in low- and middle-income countries. We conducted a cross-sectional study to determine the prevalence and the factors associated with LTBI among the inmate population detained in three Southern Italian penitentiaries. Tuberculin intradermal reaction skin test was performed on the inmates who agreed to participate in the study. In case of positivity, the QuantiFERON-TB test was performed. In those positive to QuantiFERON, chest X-ray films were performed, and treatment initiated. A total of 381 inmates accepted to participate. The prevalence of LTBI was 4.2%. In the analysis, LTBI was associated with no self-reported contact with active tuberculosis patients within the prisons, and 10% of subjects admitted the use of inhaled drugs. No HIV coinfections were found. No cases of active symptomatic tuberculosis were identified during the study period. Our results confirm that incarceration increases the risk of tuberculous infection. Non-EU nationality and a history of drug addiction appear to be major risk factors for tuberculosis infection in the penitentiary setting. Reinforcing tuberculosis control is essential to prevent its transmission in prisons.

Performance comparison of a flow cytometry immunoassay for intracellular cytokine staining and the QuantiFERON® SARS-CoV-2 test for detection and quantification of SARS-CoV-2-Spike-reactive-IFN-γ-producing T cells after COVID-19 vaccination.

PURPOSE: We compared the performance of an in-house-developed flow cytometry assay for intracellular cytokine staining (FC-ICS) and a commercially-available cytokine release assay (the QuantiFERON® SARS-CoV-2 Test [QF]) for detection and quantification of SARS-CoV-2-Spike (S)-reactive-IFN-γ-producing T cells after COVID-19 vaccination. PATIENTS AND METHODS: The sample included 141 individuals (all male; median age, 42 years; 20-72) who had been fully vaccinated with the Comirnaty® COVID-19 vaccine (at a median of 114 days; 34-145). Prior to vaccination, 91 were categorized as being SARS-CoV-2-naïve and 50 as SARS-CoV-2-experienced. A whole blood-based FC-ICS using 15-mer overlapping peptides encompassing the entire SARS-CoV-2 S protein was used for enumeration of virus-specific IFN-γ-producing CD4+ and CD8+ T cells. The QF test (Ag1 for CD4+ T cells and Ag2 for CD4+ and CD8+ T cells in combination) was carried out following the manufacturer's instructions. RESULTS: The FC-ICS and the QF assays returned significantly discordant qualitative results in both the entire cohort (P<0.001 with QF Ag1 and QF Ag2) and in SARS-CoV-2-naïve participants alone (P=0.005 and P=0.01, respectively). Discrepant results mostly involved FC-ICS positive/QF negative specimens. Overall, no correlation was found either between SARS-CoV-2 IFN-γ- CD4+ T-cell frequencies and IFN-γ levels measured in the QF Ag1 tube (P=0.78) or between the sum of SARS-CoV-2 IFN-γ CD4+ and CD8+ T-cell frequencies and IFN-γ levels quantified in the QF Ag2 tube. CONCLUSION: The data suggest a greater sensitivity for the FC-ICS assay than the QF test, and urge caution when comparing SARS-CoV-2 T-cell immune responses assessed using different analytical platforms.

In Patients with Severe COVID-19, the Profound Decrease in the Peripheral Blood T-Cell Subsets Is Correlated with an Increase of QuantiFERON-TB Gold Plus Indeterminate Rates and Reflecting a Reduced Interferon-Gamma Production.

Increased rates of indeterminate QuantiFERON-TB Gold Plus Assay (QFT-Plus) were demonstrated in patients hospitalized with Coronavirus Disease (COVID)-19. We aimed to define the prevalence and characteristics of hospitalized COVID-19 patients with indeterminate QFT-Plus. A retrospective study was performed including hospitalized COVID-19 patients, stratified in survivors and non-survivors, non-severe and severe according to the maximal oxygen supply required. Statistical analysis was performed using JASP ver0.14.1 and GraphPad Prism ver8.2.1. A total of 420 patients were included, median age: 65 years, males: 66.4%. The QFT-Plus was indeterminate in 22.1% of patients. Increased rate of indeterminate QFT-Plus was found in non-survivors (p = 0.013) and in severe COVID-19 patients (p < 0.001). Considering the Mitogen-Nil condition of the QFT-Plus, an impaired production of interferon-gamma (IFN-γ) was found in non-survivors (p < 0.001) and in severe COVID-19 patients (p < 0.001). A positive correlation between IFN-γ levels in the Mitogen-Nil condition and the absolute counts of CD3+ (p < 0.001), CD4+ (p < 0.001), and CD8+ (p < 0.001) T-lymphocytes was found. At the multivariable analysis, CD3+ T-cell absolute counts and CD4/CD8 ratio were confirmed as independent predictors of indeterminate results at the QFT-Plus. Our study confirmed the increased rate of indeterminate QFT-Plus in COVID-19 patients, mainly depending on the peripheral blood T-lymphocyte depletion found in the most severe cases.

The Role of QuantiFERON-TB Gold Plus in Mycobacterium Tuberculosis Detection in a Severe HIV Immunocompromised Patient-Case Report.

Tuberculosis (TB) is an important opportunistic infection in HIV-positive people. We are reporting a case of a 31-year-old HIV-infected patient who was hospitalized in July 2021 for dyspnea, cough with mucopurulent sputum and asthenia. He was confirmed to have Serratia liquefaciens pneumonia and acute respiratory failure. The evolution was unfavorable despite the antibiotic, pathogenic and symptomatic treatment. Because the patient had severe immunosuppression (CD4 count = 37 cell/mm3), we used QuantiFERON-TB Gold Plus for the detection of the Mycobacterium tuberculosis infection. The antituberculosis therapy was initiated, which resulted in a significant improvement of the general condition and the patient was discharged with the recommendation to continue antiretroviral therapy, antituberculosis treatment and Trimethoprim/Sulfamethoxazole-single tablet daily for the prophylaxis of Pneumocystis pneumonia.

Preliminary Evaluation of QuantiFERON SARS-CoV-2 and QIAreach Anti-SARS-CoV-2 Total Test in Recently Vaccinated Individuals.

INTRODUCTION: There is an increasing body of evidence surrounding the importance of a T cell-mediated response to SARS-CoV-2 infection and after COVID-19 vaccination. In this internal feasibility study, we evaluated both the total antibody (IgA, IgM, and IgG) and T cell responses in a cohort of COVID-19 convalescents and vaccinated individuals. METHODS: Whole blood specimens were collected weekly from 12 subjects at different time points within/after the COVID-19 mRNA vaccination regimen, and from 4 PCR-confirmed convalescent donors to measure durability of humoral and cell-mediated immune response. T cell and antibody responses were evaluated via the QuantiFERON SARS-CoV-2 research use only (QFN SARS-CoV-2) assay which is an interferon gamma release assay (IGRA) and QIAreach Anti-SARS-CoV-2 total (Anti-CoV-2) test, respectively. RESULTS: In a cohort of recently vaccinated individuals, subjects demonstrated robust total antibody and CD4+/CD8+ T cell response to SARS-CoV-2 mRNA vaccines when followed for 2 months post-2nd dose. In most individuals, T cell response declined between the 1st and 2nd doses suggesting a need for a booster or the completion of the 2-dose vaccine series. In a group of convalescent donors tested with QFN SARS-CoV-2 and Anti-CoV-2 tests, all patients had an antibody and T cell response up to 1 year after natural infection. CONCLUSION: This small feasibility study demonstrates that the QFN-SARS-CoV-2 test is able to identify CD4+ and CD8+ T cell-mediated responses in SARS-CoV-2-vaccinated subjects and those recovered from COVID-19, alongside a qualitative antibody response detectable via the QIAreach Anti-CoV2 test.