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 aim of this study was to evaluate the role of baseline lymphocyte subset counts in predicting the outcome and severity of COVID-19 patients. Hospitalized patients confirmed to be infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were included and classified according to in-hospital mortality (survivors/nonsurvivors) and the maximal oxygen support/ventilation supply required (nonsevere/severe). Demographics, clinical and laboratory data, and peripheral blood lymphocyte subsets were retrospectively analyzed. Overall, 160 patients were retrospectively included in the study. T-lymphocyte subset (total CD3+, CD3+ CD4+, CD3+ CD8+, CD3+ CD4+ CD8+ double positive [DP] and CD3+ CD4− CD8− double negative [DN]) absolute counts were decreased in nonsurvivors and in patients with severe disease compared to survivors and nonsevere patients (p < 0.001). Multivariable logistic regression analysis showed that absolute counts of CD3+ T-lymphocytes < 524 cells/µl, CD3+ CD4+ < 369 cells/µl, and the number of T-lymphocyte subsets below the cutoff (T-lymphocyte subset index [TLSI]) were independent predictors of in-hospital mortality. Baseline T-lymphocyte subset counts and TLSI were also predictive of disease severity (CD3+  < 733 cells/µl; CD3+ CD4+ < 426 cells/µl; CD3+ CD8+ < 262 cells/µl; CD3+ DP < 4.5 cells/µl; CD3+ DN < 18.5 cells/µl). The evaluation of peripheral T-lymphocyte absolute counts in the early stages of COVID-19 might represent a useful tool for identifying patients at increased risk of unfavorable outcomes.

Background: Recently SARS-CoV-2 has spread worldwide causing a pandemic. Little is known about disease severity in immunocompromised hosts and people receiving disease modifying therapies (DMTs). In the last decades DMTs have been widely employed, and ocrelizumab represents one of the newest therapies for the relapsing remitting and progressive forms of multiple sclerosis (MS). Objectives: to describe SARS-CoV-2 related pneumonia in two MS patients under ocrelizumab treatment. Methods: Case series. Results: Patients showed a mild clinical course of SARS-CoV-2 related pneumonia without complications or sequelae. Conclusion: Ocrelizumab treatment is not necessarily associated to increased severity in MS patients with SARS-CoV-2 infection.

Background Cell-mediated immunity (CMI) after anti-Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 vaccines has been poorly explored in recipients of allogeneic hematopoietic stem-cell transplantation (HSCT), especially with regard to the 3rd dose (booster). Aim of the study was to assess the specific T-cell responses before and after the 3rd dose of BNT162b2 mRNA vaccine in a cohort of allogeneic HSCT recipients, and compare it with healthy donors (HD). Methods Allogenic HSCT recipients and HD were enrolled before receiving the 3rd dose of BNT162b2 mRNA vaccine. Whole blood for T-cell specific responses was collected before (T1) and 8 weeks after (T2) the booster administration. T-cell responses were assessed with an Interferon (IFN)-γ release assay (IGRA), after overnight stimulation of heparin whole blood with pools of lyophilized peptides, covering the immunodominant sequence of the Spike (S) protein. IFN-γ production was assessed with an enzyme linked immunosorbent assay (ELISA). Statistical analysis was performed with GraphPadPrism. Results 14 HSCT recipients (8M, 6F) and 15 HD (7M, 8F) were enrolled (table 1). Median age was 47 [39-59] and 41 [31-48] years in the HSCT and HD groups, respectively. Time between the vaccine 2nd dose and T1 was significantly longer in HD than HSCT recipients (p&lt; .001), while the time between T1 and T2 did not differ between the two groups. SARS-CoV-2 S specific T-cell responses at T1 were inferior in HSCT recipients compared to HD (median IFN-γ production: 463 vs 231 ng/ml, respectively), although the difference did not reach the statistical significance. No differences were observed at T2. In a before-after analysis, SARS-CoV-2 S specific T-cell responses were significantly increased in HSCT recipients at T2 compared to T1 (median IFN-γ production: 267 vs 881 ng/ml, p=0.02) (Figure 1). At T1, 3 HSCT recipients showed very low or no IFN-γ production, while at T2 only 1 patient still had undetectable IFN-γ production after S peptide stimulation. Table 1:Clinical characteristics of allo-HSCT recipients and HDHSCT: hematopoietic stem-cell transplantation; IQR: interquartile range; ALL: acute lymphoblastic leukemia; AML: acute myeloid leukemia; MDS: myelodysplastic syndrome; T-ALL: T-cell acute lymphoblastic leukemia; AA: aplastic anemia; PMF: primary myelofibrosis; MUD: matched unrelated donor; MMUD: mismatched unrelated donors; NA: not applicable; ns: not significant.Figure 1:IFN-γ Production after Spike peptide stimulation of whole blood from allogenic HSCT recipients and HD.Comparison of IFN-γ production after Spike peptide stimulation of whole blood in allogenic HSCT recipients and HD at T1 (1.A) and T2 (1.B) (before and after BNT162b2 mRNA vaccine 3rd dose, respectively). Before-after representation of IFN-γ production after Spike peptide stimulation in HD and allogenic HSCT recipients (1.C). Conclusion SARS-CoV-2 IGRA represents a useful tool to assess CMI, also in immunocompromised hosts. An additional 3rd BNT162b2 mRNA vaccine booster dose seems to enhance CMI in allogenic HSCT recipients. Further studies are needed to evaluate the duration of SARS-CoV-2 CMI in HSCT recipients compared to HD. Disclosures All Authors: No reported disclosures.