Detection of Mycobacterium tuberculosis DNA in CD34+ peripheral blood mononuclear cells of adults with tuberculosis infection and disease.

OBJECTIVES: To investigate whether Mycobacterium tuberculosis (Mtb) DNA is detected in peripheral blood mononuclear cells (PBMC) of subjects with tuberculosis (TB) or TB infection (TBI) living in a low-burden country. METHODS: We prospectively enrolled 57 patients with TB, 41 subjects with TBI, and 39 controls in Rome, Italy. PBMC were isolated, cluster of differentiation (CD)34+ and CD34- cells were immunomagnetic separated, DNA was extracted, and digital polymerase chain reaction for IS6110 and rpoB sequences was used to detect Mtb DNA in PBMC subsets and unfractionated PBMC. RESULTS: We detected Mtb DNA at a low copy number in CD34+ cells in 4o f 30 (13%) patients with TB, 2 of 24 (8%) subjects with TBI, and 1 of 24 (4%) controls. Mtb DNA was detected in unfractionated PBMC in 3 of 51 (6%) patients with TB, 2 of 38 (5%) subjects with TBI, and 2 of 36 (6%) controls. In CD34- cells, only 1 of 31 (3%) subjects with TBI tested positive for Mtb DNA. CONCLUSIONS: Mtb DNA was detected at low frequencies and levels in the PBMC of subjects with TBI and donors with TB living in a low-burden country. In particular, Mtb DNA was detected more frequently in CD34+ cells, supporting the hypothesis that these cells may represent a Mtb niche. This finding informs biological understanding of Mtb pathogenesis and may support the development of a microbial blood biomarker for Mtb infection.

Association between sex hormones and anti-S/RBD antibody responses to COVID-19 vaccines in healthcare workers.

Healthcare workers (HCWs) are the target population for vaccination against coronavirus disease (COVID-19) as they are at a high risk of exposure and transmission of pathogens to patients. Neutralizing antibodies developed after COVID-19 vaccination decline within few months of vaccination. Several factors, including age and sex, can affect the intensity, efficacy, and duration of immune response to vaccines. However, sex-specific analyses of humoral responses to COVID-19 vaccines are lacking. This study aimed to evaluate sex-based differences in anti-S/RBD (Receptor Binding Domain) responses at three different time points after the second dose of mRNA COVID-19 vaccine in HCWs in relation to age, and to investigate the role of sex hormones as potential markers of response. Anti-S/RBD levels after two doses of the mRNA vaccine were collected from 521 HCWs naïve to COVID-19, working at two Italian Clinical Centers. Multiple regression analysis was applied to evaluate the association between anti-S levels and sex, age, and plasma levels of sex hormones. Significantly higher anti-S/RBD response to the COVID-19 vaccination was found in female HCWs, and a significant and more abrupt decline in response with time was observed in women than that in men. A novel, positive association of testosterone plasma levels and higher anti-S levels in male HCWs was found, suggesting its potential role as sex specific marker in males. In conclusion, understanding the sex-based differences in humoral immune responses to vaccines may potentially improve vaccination strategies and optimize surveillance programs for HCWs.

Older Age, a High Titre of Neutralising Antibodies and Therapy with Conventional DMARDs Are Associated with Protection from Breakthrough Infection in Rheumatoid Arthritis Patients after the Booster Dose of Anti-SARS-CoV-2 Vaccine.

Objectives: We aimed to analyse the incidence and severity of breakthrough infections (BIs) in rheumatoid arthritis (RA) patients after a COronaVIrus Disease 2019 (COVID-19) vaccination booster dose. Methods: We enrolled 194 RA patients and 1002 healthcare workers (HCWs) as controls. Clinical, lifestyle and demographic factors were collected at the time of the third dose, and immunogenicity analyses were carried out in a subgroup of patients at 4-6 weeks after the third dose. Results: BIs were experienced by 42% patients (82/194) with a median time since the last vaccination of 176 days. Older age (>50 years; aHR 0.38, 95% CI: 0.20-0.74), receiving conventional synthetic disease modifying antirheumatic drugs (csDMARDs) (aHR 0.52, 95%CI: 0.30-0.90) and having a titre of neutralising antibodies >20 (aHR 0.36, 95% CI: 0.12-1.07) were identified as protective factors. Conversely, anti-IL6R treatment and anti-CD20 therapy increased BI probability. BIs were mostly pauci-symptomatic, but the hospitalisation incidence was significantly higher than in HCWs (8.5% vs. 0.19%); the main risk factor was anti-CD20 therapy. Conclusions: Being older than 50 years and receiving csDMARDs were shown to be protective factors for BI, whereas anti-IL6R or anti-CD20 therapy increased the risk. Higher neutralising antibody titres were associated with a lower probability of BI. If confirmed in a larger population, the identification of a protective cut-off would allow a personalised risk-benefit therapeutic management of RA patients.

Evaluation of Cross-Immunity to the Mpox Virus Due to Historic Smallpox Vaccination.

When the Mpox virus (MPXV) began spreading globally in 2022, it became critical to evaluate whether residual immunity from smallpox vaccination provided cross-protection. To assess the cross-immune response to MPXV, we collected serum samples (n = 97) and PBMCs (n = 30) from healthy-donors, either born before 1974 and reporting smallpox vaccination during childhood or born after 1975 and not vaccinated with Vaccinia virus (VACV)-based vaccines. We evaluated the levels of anti-MPXV IgG and neutralizing antibodies (Nabs) and the presence of a T cell response against MPXV. We found anti-MPXV IgG and Nabs in 60 (89.6%) and 40 (70.1%) vaccinated individuals, respectively. We observed a T cell response to Orthopoxviruses and MPXV peptide pools in 30% of vaccinated individuals. We thus show that a high proportion of subjects who received the smallpox vaccine 40 to 60 years ago have humoral cross-immunity, while the T-cell-specific response against MPXV was observed in a smaller group (30%) of vaccinated individuals. This study, combined with information on immunity developed during natural infection or the administration of current vaccines, will contribute to a better understanding of humoral and cellular responses against MPXV.

Kinetics of TTV Loads in Peripheral Blood Mononuclear Cells of Early Treated Acute HIV Infections.

Torquetenovirus (TTV) is the most abundant component of the human blood virome and its replication is controlled by a functioning immune system. In this study, TTV replication was evaluated in 21 people with acute HIV infection (AHI) and immune reconstitution following antiretroviral therapy (ART). PBMC-associated TTV and HIV-1 DNA, as well as plasma HIV-1 RNA, were measured by real-time PCR. CD4 and CD8 differentiation, activation, exhaustion, and senescence phenotypes were analyzed by flow cytometry. Thirteen healthy donors (HD) and twenty-eight chronically infected HIV individuals (CHI), late presenters at diagnosis, were included as control groups. TTV replication in AHI seems to be controlled by the immune system being higher than in HD and lower than in CHI. During ART, a transient increase in TTV DNA levels was associated with a significant perturbation of activation and senescence markers on CD8 T cells. TTV loads were positively correlated with the expansion of CD8 effector memory and CD57+ cells. Our results shed light on the kinetics of TTV replication in the context of HIV acute infection and confirm that the virus replication is strongly regulated by the modulation of the immune system.

SARS-CoV-2 Breakthrough Infections According to the Immune Response Elicited after mRNA Third Dose Vaccination in COVID-19-Naïve Hospital Personnel.

BACKGROUND: Vaccine-induced SARS-CoV-2-anti-spike antibody (anti-S/RBD) titers are often used as a marker of immune protection and to anticipate the risk of breakthrough infections, although no clear cut-off is available. We describe the incidence of SARS-CoV-2 vaccine breakthrough infections in COVID-19-free personnel of our hospital, according to B- and T-cell immune response elicited one month after mRNA third dose vaccination. METHODS: The study included 487 individuals for whom data on anti-S/RBD were available. Neutralizing antibody titers (nAbsT) against the ancestral Whuan SARS-CoV-2, and the BA.1 Omicron variant, and SARS-CoV-2 T-cell specific response were measured in subsets of 197 (40.5%), 159 (32.6%), and 127 (26.1%) individuals, respectively. RESULTS: On a total of 92,063 days of observation, 204 participants (42%) had SARS-CoV-2 infection. No significant differences in the probability of SARS-CoV-2 infection for different levels of anti-S/RBD, nAbsT, Omicron nAbsT, or SARS-CoV-2 T cell specific response, and no protective thresholds for infection were found. CONCLUSIONS: Routine testing for vaccine-induced humoral immune response to SARS-CoV-2 is not recommended if measured as parameters of 'protective immunity' from SARS-CoV-2 after vaccination. Whether these findings apply to new Omicron-specific bivalent vaccines is going to be evaluated.

Humoral Immune Response after COVID-19 mRNA Vaccination in Patients with Liver Cirrhosis: A Prospective Real-Life Single Center Study.

Coronavirus-disease-2019 (COVID-19) mRNA vaccination effectively reduces mortality and morbidity in cirrhotic patients, but the immunogenicity and safety of vaccination have been partially characterized. The study aimed to evaluate humoral response, predictive factors, and safety of mRNA-COVID-19 vaccination in cirrhotic patients compared to healthy subjects. A prospective, single-center, observational study enrolled consecutive cirrhotic patients who underwent mRNA-COVID-19 vaccination from April to May 2021. Anti-spike-protein (anti-S) and nucleocapsid-protein (anti-N) antibodies were evaluated before the first (T0) and the second (T1) doses and 15 days after completing the vaccination. An age and sex-matched healthy reference group was included. The incidence of adverse events (AEs) was assessed. In total, 162 cirrhotic patients were enrolled, 13 were excluded due to previous SARS-CoV-2 infection; therefore, 149 patients and 149 Health Care Workers (HCWs) were included in the analysis. The seroconversion rate was similar in cirrhotic patients and HCWs at T1 (92.5% vs. 95.3%, p = 0.44) and T2 (100% in both groups). At T2, anti-S-titres were significantly higher in cirrhotic patients compared to HCWs (2776.6 vs. 1756 BAU/mL, p < 0.001]. Male sex (ß = -0.32 [-0.64, -0.04], p = 0.027) and past-HCV-infection (ß = -0.31 [-0.59, -0.04], p = 0.029) were independent predictors of lower anti-S-titres on multiple-gamma-regression-analysis. No severe AEs occurred. The COVID-19-mRNA vaccination induces a high immunization rate and anti-S-titres in cirrhotic patients. Male sex and past-HCV infection are associated with lower anti-S-titres. The COVID-19-mRNA vaccination is safe.

Dynamic Evolution of Humoral and T-Cell Specific Immune Response to COVID-19 mRNA Vaccine in Patients with Multiple Sclerosis Followed until the Booster Dose.

This study characterizes antibody and T-cell immune responses over time until the booster dose of COronaVIrus Disease 2019 (COVID-19) vaccines in patients with multiple sclerosis (PwMS) undergoing different disease-modifying treatments (DMTs). We prospectively enrolled 134 PwMS and 99 health care workers (HCWs) having completed the two-dose schedule of a COVID-19 mRNA vaccine within the last 2-4 weeks (T0) and followed them 24 weeks after the first dose (T1) and 4-6 weeks after the booster (T2). PwMS presented a significant reduction in the seroconversion rate and anti-receptor-binding domain (RBD)-Immunoglobulin (IgG) titers from T0 to T1 (p < 0.0001) and a significant increase from T1 to T2 (p < 0.0001). The booster dose in PwMS showed a good improvement in the serologic response, even greater than HCWs, as it promoted a significant five-fold increase of anti-RBD-IgG titers compared with T0 (p < 0.0001). Similarly, the T-cell response showed a significant 1.5- and 3.8-fold increase in PwMS at T2 compared with T0 (p = 0.013) and T1 (p < 0.0001), respectively, without significant modulation in the number of responders. Regardless of the time elapsed since vaccination, most ocrelizumab- (77.3%) and fingolimod-treated patients (93.3%) showed only a T-cell-specific or humoral-specific response, respectively. The booster dose reinforces humoral- and cell-mediated-specific immune responses and highlights specific DMT-induced immune frailties, suggesting the need for specifically tailored strategies for immune-compromised patients to provide primary prophylaxis, early SARS-CoV-2 detection and the timely management of COVID-19 antiviral treatments.

Third dose of SARS-CoV2 mRNA vaccination produces robust persistent cellular and humoral immune responses in liver transplant recipients.

Weaker responses have been described after two doses of anti-SARS-CoV2 vaccination in liver transplant recipients (LTRs). At the Italian National Institute for Infectious Diseases, 122 LTRs (84% males, median age 64 years) were tested for humoral and cell-mediated immune response after a third doses of anti-SARS-CoV2 mRNA vaccines. Humoral response was measured by quantifying anti-receptor binding domain and neutralizing antibodies; cell-mediated response was measured by quantifying IFN-γ after stimulation of T cells with SARS-CoV-2-specific peptides. Humoral and cellular responses improved significantly compared to the second vaccine dose; 86.4% of previous non-responders to the first 2 vaccine doses (N = 22) became responders. Mycophenolate mofetil-containing regimens were not associated with lower response rates to a third vaccine; shorter time since transplantation (<6 years) was associated with lower humoral and cellular responses to third vaccine. Protective antibodies against Omicron variant were detected in 60% of patients 12 weeks after third vaccine dose.

Longitudinal characterisation of B and T-cell immune responses after the booster dose of COVID-19 mRNA-vaccine in people with multiple sclerosis using different disease-modifying therapies.

BACKGROUND: The decline of humoral response to COVID-19 vaccine led to authorise a booster dose. Here, we characterised the kinetics of B-cell and T-cell immune responses in patients with multiple sclerosis (PwMS) after the booster dose. METHODS: We enrolled 22 PwMS and 40 healthcare workers (HCWs) after 4-6 weeks from the booster dose (T3). Thirty HCWs and 19 PwMS were also recruited 6 months (T2) after the first dose. Antibody response was measured by anti-receptor-binding domain (RBD)-IgG detection, cell-mediated response by an interferon (IFN)-γ release assay (IGRA), Th1 cytokines and T-cell memory profile by flow cytometry. RESULTS: Booster dose increased anti-RBD-IgG titers in fingolimod-treated, cladribine-treated and IFN-ß-treated patients, but not in ocrelizumab-treated patients, although antibody titres were lower than HCWs. A higher number of fingolimod-treated patients seroconverted at T3. Differently, T-cell response evaluated by IGRA remained stable in PwMS independently of therapy. Spike-specific Th1-cytokine response was mainly CD4+ T-cell-mediated, and in PwMS was significantly reduced (p<0.0001) with impaired IL-2 production compared with HCWs at T3. In PwMS, total Th1 and IFN-γ CD4+ T-cell responders to spike protein were increased from T2 to T3.Compared with HCWs, PwMS presented a higher frequency of CD4+ and CD8+ terminally differentiated effector memory cells and of CD4+ effector memory (TEM) cells, independently of the stimulus suggesting the association of this phenotype with MS status. CD4+ and CD8+ TEM cell frequency was further increased at T3 compared with T2. CONCLUSIONS: COVID-19 vaccine booster strengthens humoral and Th1-cell responses and increases TEM cells in PwMS.

Intact provirus and integration sites analysis in acute HIV-1 infection and changes after one year of early antiviral therapy.

Background and objectives: HIV-1 provirus integration in host genomes provides a lifelong reservoir of virally infected cells. Although not able to generate viral progeny, the expression of defective proviruses has been associated with activation. Provirus integration may influence host gene transcription and shifts may occur during disease progression or antiretroviral therapy (ART). The study aimed to analyze intact/defective provirus and sites of provirus integration in acute infections: changes after 48 weeks of early therapy were also evaluated. Methods: DNA from peripheral blood lymphomonocytes of 8 acute HIV-1 infections at serodiagnosis (T0) and after 48 weeks of therapy (T1) was used to quantify intact and defective provirus by digital-droplet PCR and to analyze provirus integration sites, by next-generation sequencing of libraries derived from ligation-mediated PCR. Results: A high variability in the amount of intact proviral DNA was observed at both T0 and T1, in the different subjects. Although the ratio of intact/total proviral HIV-1 DNA did not dramatically change between T0 (8.05%) and T1 (9.34%), after early therapy both intact and total HIV-1 DNA declined significantly, p = 0.047 and p = 0.008, respectively. The median number of different (IQR) integration sites in human chromosomes/subject was 5 (2.25-13.00) at T0 and 4 (3.00-6.75) at T1. Of all the integration sites observed at T1, 64% were already present at T0. Provirus integration was observed in introns of transcriptionally active genes. Some sites of integration, among which the most represented was in the neuregulin 2 gene, were shared by different patients, together with the orientation of the insertion. Provirus integration was also observed in intergenic regions, with median (IQR) % of 15.13 (6.81-21.40) at T0 and 18.46 (8.98-22.18) at T1 of all read matches. Conclusions: In acute HIV-1 infection, the amount of intact proviral DNA in peripheral lymphomonocytes did not exceed 10% of total HIV-1 DNA, a percentage that was not substantially changed by early administrated ART. Provirus displayed a relatively small number of recurrent integration sites in introns of transcriptionally active genes, mainly related to cell-cycle control. Consideration should be given to therapeutic strategies able to target the cells harboring defective proviruses, that are not reached by conventional antiviral drugs, these potentially also impacting on replicative competent integrated provirus.

Booster dose of SARS-CoV-2 messenger RNA vaccines strengthens the specific immune response of patients with rheumatoid arthritis: A prospective multicenter longitudinal study.

OBJECTIVES: To characterize the kinetics of humoral and T-cell responses in rheumatoid arthritis (RA)-patients followed up to 4-6 weeks (T3) after the SARS-CoV-2 vaccine booster dose. METHODS: Health care workers (HCWs, n = 38) and patients with RA (n = 52) completing the messenger RNA vaccination schedule were enrolled at T3. In each cohort, 25 subjects were sampled after 5 weeks (T1) and 6 months (T2) from the first vaccine dose. The humoral response was assessed by measuring anti-receptor-binding domain (RBD) and neutralizing antibodies, the T-cell response by interferon-γ-release assay (IGRA), T cell cytokine production, and B cell phenotype at T3 by flow cytometry. RESULTS: Patients with RA showed a significant reduction of antibody titers from T1 to T2 and a significant increase at T3. T-cell response by IGRA persisted over time in patients with RA, whereas it increased in HCWs. Most patients with RA scored positive for anti-RBD, neutralizing antibody and T-cell responses, although the magnitude was lower than HCWs. The spike-specific-cytokine response was mainly clusters of differentiation (CD)4+ T cells restricted in both cohorts and significantly lower with reduced interleukin-2 response and CD4-antigen-responding naïve T cells in patients with RA. Unswitched memory B cells were reduced in patients with RA compared with HCWs independently of vaccination. CONCLUSION: COVID-19 vaccine booster strengthens the humoral immunity in patients with RA even with a reduced cytokine response.

Prevention from Sharp Injuries in the Hospital Sector: An Italian National Observatory on the Implementation of the Council Directive 2010/32/EU before and during the COVID-19 Pandemic.

Sharp injuries, determining the risk of bloodborne infections and psychological distress in healthcare workers, may be prevented by a set of strategies, legally enforced in Europe through the Directive 2010/32/EU. To assess its level of implementation in Italy, a national survey was conducted in 2017 and again in 2021, evaluating the progress and possible drawbacks of the COVID-19 pandemic. Altogether, 285 safety managers and 330 nurses from a representative sample of 97 and 117 public hospitals were interviewed using a standardized questionnaire. Knowledge of the Directive requirements decreased significantly, with <60% of participants answering correctly in 2021, and nurses' attendance in specific courses dropped to 25% in 2021 compared to 54% in 2017. Over 75% of hospitals introduced multiple safety-engineered devices (SED), though total replacement occurred in <50% of cases; routine SED availability increased for blood collection (89%) and venous access devices (83%). Incorrect behaviors in handling sharps decreased significantly over time. Nurses' HBV vaccination coverage was high (89% in both surveys); in the last year, 97% were vaccinated against COVID, and 47% against influenza. Average annual injuries per hospital did not increase significantly (32 in 2021 vs. 26 in 2017). In 2017, nurses' perceived safety barriers were working in emergency situations (49%) and lack of resources (40%); in 2021, understaffing (73%), physical fatigue (62%), and handling difficulties while wearing full protective equipment (59%). Safety measures were implemented in Italian hospitals, and although the average injuries per hospital did not show a decrease, these measures could have helped protect healthcare workers during the pandemic, mitigating its potential impact on the increase in situations at risk of injury.

SARS-CoV-2 Omicron Variant Neutralization after Third Dose Vaccination in PLWH.

The aim was to measure neutralizing antibody levels against the SARS-CoV-2 Omicron (BA.1) variant in serum samples obtained from vaccinated PLWH and healthcare workers (HCW) and compare them with those against the Wuhan-D614G (W-D614G) strain, before and after the third dose of a mRNA vaccine. We included 106 PLWH and 28 HCWs, for a total of 134 participants. Before the third dose, the proportion of participants with undetectable nAbsT against BA.1 was 88% in the PLWH low CD4 nadir group, 80% in the high nadir group and 100% in the HCW. Before the third dose, the proportion of participants with detectable nAbsT against BA.1 was 12% in the PLWH low nadir group, 20% in the high nadir group and 0% in HCW, respectively. After 2 weeks from the third dose, 89% of the PLWH in the low nadir group, 100% in the high nadir group and 96% of HCW elicited detectable nAbsT against BA.1. After the third dose, the mean log2 nAbsT against BA.1 in the HCW and PLWH with a high nadir group was lower than that seen against W-D614G (6.1 log2 (±1.8) vs. 7.9 (±1.1) and 6.4 (±1.3) vs. 8.6 (±0.8)), respectively. We found no evidence of a different level of nAbsT neutralization by BA.1 vs. W-D614G between PLWH with a high CD4 nadir and HCW (0.40 (−1.64, 2.43); p = 0.703). Interestingly, in PLWH with a low CD4 nadir, the mean log2 difference between nAbsT against BA.1 and W-D614G was smaller in those with current CD4 counts 201−500 vs. those with CD4 counts < 200 cells/mm3 (−0.80 (−1.52, −0.08); p = 0.029), suggesting that in this target population with a low CD4 nadir, current CD4 count might play a role in diversifying the level of SARS-CoV-2 neutralization.

Immunogenicity to COVID-19 mRNA vaccine third dose in people living with HIV.

In order to investigate safety and immunogenicity of SARS-CoV-2 vaccine third dose in people living with HIV (PLWH), we analyze anti-RBD, microneutralization assay and IFN-γ production in 216 PLWH on ART with advanced disease (CD4 count <200 cell/mm3 and/or previous AIDS) receiving the third dose of a mRNA vaccine (BNT162b2 or mRNA-1273) after a median of 142 days from the second dose. Median age is 54 years, median CD4 nadir 45 cell/mm3 (20-122), 93% HIV-RNA < 50 c/mL. In 68% of PLWH at least one side-effect, generally mild, is recorded. Humoral response after the third dose was strong and higher than that achieved with the second dose (>2 log2 difference), especially when a heterologous combination with mRNA-1273 as third shot is used. In contrast, cell-mediated immunity remain stable. Our data support usefulness of third dose in PLWH currently receiving suppressive ART who presented with severe immune dysregulation.

Pillars for prevention and control of healthcare-associated infections: an Italian expert opinion statement.

Healthcare-associated infections (HAIs) represent a relevant problem for all healthcare facilities, because they involve both the care aspect and the economic management of the hospital. Most HAIs are preventable through effective Infection Prevention and Control (IPC) measures. Implementation and improvement of IPC programs are critical to reducing the impact of these infections and the spread of multi-resistant microorganisms. The purpose of this Expert Opinion statement was to provide a practical guide for healthcare organizations, physicians, and nursing staff on the optimal implementation of the core components of Infection Prevention and Control, as recommended by a board of specialists after in-depth discussion of the available evidence in this field. According to their independent suggestions and clinical experiences, as well as evidence-based practices and literature review, this document provides a practical bundle of organizational, structural, and professional requirements necessary to promote, through multimodal strategies, the improvement of the quality and safety of care with respect to infectious risk in order to protect the patient, facilities, and healthcare providers.

Epidemiological, clinical and virological characteristics of four cases of monkeypox support transmission through sexual contact, Italy, May 2022.

Since May 2022, an outbreak of monkeypox has been ongoing in non-endemic countries. We report four cases in Italy in young adult men reporting condomless sexual intercourse. The patients are in good clinical condition with no need for specific antiviral drugs. Biological samples from seminal fluid were positive for monkeypox viral DNA. For many other viruses found in semen there is no evidence of sexual transmission. The possibility of sexual transmission of monkeypox virus needs to be investigated.

Retention of Neutralizing Response against SARS-CoV-2 Omicron Variant in Sputnik V-Vaccinated Individuals.

The new Omicron variant of SARS-CoV-2, first identified in November 2021, is rapidly spreading all around the world. Omicron has become the dominant variant of SARS-CoV-2. There are many ongoing studies evaluating the effectiveness of existing vaccines. Studies on the neutralizing activity of vaccinated sera against the Omicron variant are currently being carried out in many laboratories. In this study, we have shown the neutralizing activity of sera against the SARS-CoV-2 Omicron variant compared to the reference Wuhan D614G variant in individuals vaccinated with two doses of Sputnik V up to 6 months after vaccination and in individuals who experienced SARS-CoV-2 infection either before or after vaccination. As a control to our study we also measured neutralizing antibody titers in individuals vaccinated with two doses of BNT162b2. The decrease in NtAb titers to the Omicron variant was 8.1-fold for the group of Sputnik V-vaccinated individuals. When the samples were stratified for the time period after vaccination, a 7.6-fold or 8.8-fold decrease in NtAb titers was noticed after up to 3 and 3-to-6 months after vaccination. We observed a 6.7- and 5-fold decrease in Sputnik V-vaccinated individuals experiencing asymptomatic or symptomatic infection, respectively. These results highlight the observation that the decrease in NtAb to the SARS-CoV-2 Omicron variant compared to the Wuhan variant occurs for different COVID-19 vaccines in use, with some showing no neutralization at all, confirming the necessity of a third booster vaccination.

Persistent Spike-specific T cell immunity despite antibody reduction after 3 months from SARS-CoV-2 BNT162b2-mRNA vaccine.

Vaccine is the main public health measure to reduce SARS-CoV-2 transmission and hospitalization, and a massive scientific effort worldwide resulted in the rapid development of effective vaccines. This work aimed to define the dynamics and persistence of humoral and cell-mediated immune response in Health Care Workers who received a two-dose BNT162b2-mRNA vaccination. Serological response was evaluated by quantifying anti-RBD and neutralizing antibodies while cell-mediated response was performed by a whole blood test quantifying Th1 cytokines (IFN-γ, TNF-α, IL-2) produced in response to Spike peptides. BNT162b2-mRNA vaccine induced both humoral and cell-mediated immune response against Spike in all HCW early after the second dose. After 12 weeks from vaccination, the titer of anti-RBD antibodies as well as their neutralization function decreased while the Spike-specific T-cells persisted at the same level as soon after vaccine boost. Of note, a correlation between cellular and humoral response persevered, suggesting the persistence of a coordinated immune response. The long lasting cell-mediated immune response after 3 months from vaccination highlight its importance in the maintaining of specific immunity able to expand again to fight eventual new antigen encountering.