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

Interferon-γ Release Assay in the Assessment of Cellular Immunity-A Single-Centre Experience with mRNA SARS-CoV-2 Vaccine in Patients with Juvenile Idiopathic Arthritis

Background: As the SARS-CoV-2 virus remains one of the main causes of severe respiratory system infections, the Food and Drug Administration strongly advises the continuation of current vaccination programs, including the distribution of updated boosters, especially in high-risk groups of patients. Therefore, there is an unceasing need for further research on the safety and, no less importantly, the clinical effectivity of the vaccines, with an extra focus on cohorts of patients with underlying health problems. This study aimed to assess the efficacy of the SARS-CoV-2 vaccine in possibly immunocompromised children with rheumatic disease while utilizing the interferon-gamma release assay (IGRA) as a marker for COVID-19 immunity in the study follow-up. Methods: This prospective study was performed in a group of 55 pediatric patients diagnosed with juvenile idiopathic arthritis. Eight participants were immunized with the Comirnaty mRNA vaccine before the research commenced, while the rest of the group (n = 47) had not been vaccinated against SARS-CoV-2. At the study baseline, the cellular response to the virus antigen was measured using a specific quantitative IGRA in whole blood; subsequently, the anti-SARS-CoV-2 test was performed, marking the antibodies' levels in serum. Around four months after the enrollment of the last patient in the study, a follow-up survey regarding the events of COVID-19 infection within the cohort was conducted. Results: The study confirmed that all the vaccinated children developed specific T-cell (p = 0.0016) and humoral (p = 0.001 for IgA antibodies, p = 0.008 for IgG antibodies) responses to the inoculation, including those receiving biological treatment and those on conventional disease-modifying anti-rheumatic drugs. The study also showed the different patterns of immunity elicited both after infection and post-vaccination, with higher levels of antibodies and T-cell response after inoculation than after natural exposure to the pathogen. According to the follow-up survey, six children developed PCR-confirmed SARS-CoV-2 infection, whereas the additional 10 patients admitted to having COVID-like symptoms with no laboratory verification. Conclusions: SARS-CoV-2 vaccinations elicit valid immune responses in pediatric rheumatic patients. Including the assessment of T-cell immunity in the evaluation of inoculation-induced immunization can enhance the accuracy of sole humoral response assays.

The immune response to SARS-CoV-2 in people with HIV

This review examines the intersection of the HIV and SARS-CoV-2 pandemics. People with HIV (PWH) are a heterogeneous group that differ in their degree of immune suppression, immune reconstitution, and viral control. While COVID-19 in those with well-controlled HIV infection poses no greater risk than that for HIV-uninfected individuals, people with advanced HIV disease are more vulnerable to poor COVID-19 outcomes. COVID-19 vaccines are effective and well tolerated in the majority of PWH, though reduced vaccine efficacy, breakthrough infections and faster waning of vaccine effectiveness have been demonstrated in PWH. This is likely a result of suboptimal humoral and cellular immune responses after vaccination. People with advanced HIV may also experience prolonged infection that may give rise to new epidemiologically significant variants, but initiation or resumption of antiretroviral therapy (ART) can effectively clear persistent infection. COVID-19 vaccine guidelines reflect these increased risks and recommend prioritization for vaccination and additional booster doses for PWH who are moderately to severely immunocompromised. We recommend continued research and monitoring of PWH with SARS-CoV-2 infection, especially in areas with a high HIV burden.

Multi-epitopes vaccine design for surface glycoprotein against SARS-CoV-2 using immunoinformatic approach

Background

The recent COVID vaccinations have successfully reduced death and severity but did not stop the transmission of viruses by the emerging SARS-CoV-2 strain. There is a need for better and long-lasting dynamic vaccines for numerous prevailing strains and the evolving SARS-CoV-2 virus, necessitating the development of broad-spectrum strains being used to stop infection by reducing the spread rate and re-infection. The spike (S) glycoprotein is one of the proteins expressed commonly in the early phases of SARS-CoV-2 infection. It has been identified as the most immunogenic protein of SARS-CoV-2.

Methods

In this study, advanced bioinformatics techniques have been exploited to design the novel multi-epitope vaccine using conserved S protein portions from widespread strains of SARS-CoV-2 to predict B cell and T cell epitopes. These epitopes were selected based on toxicity, antigenicity score and immunogenicity. Epitope combinations were used to construct the maximum potent multi-epitope construct with potential immunogenic features. EAAAK, AAY, and GPGPG were used as linkers to construct epitopes.

Results

The developed vaccine has shown positive results. After the chimeric vaccine construct was cloned into the PET28a (+) vector for expression screening in Escherichia coli, the potential expression of the construct was identified.

Conclusion

The construct vaccine performed well in computer-based immune response simulation and covered a variety of allelic populations. These computational results are more helpful for further analysis of our contract vaccine, which can finally help control and prevent SARS-CoV-2 infections worldwide.

Intradermal Fractional ChAdOx1 nCoV-19 Booster Vaccine Induces Memory T Cells: A Follow-Up Study

The administration of viral vector and mRNA vaccine booster effectively induces humoral and cellular immune responses. Effector T cell responses after fractional intradermal (ID) vaccination are comparable to those after intramuscular (IM) boosters. Here, we quantified T cell responses after booster vaccination. ChAdOx1 nCoV-19 vaccination induced higher numbers of S1-specific CD8+ memory T cells, consistent with the antibody responses. Effector memory T cell phenotypes elicited by mRNA vaccination showed a similar trend to those elicited by the viral vector vaccine booster. Three months post-vaccination, cytokine responses remained detectable, confirming effector T cell responses induced by both vaccines. The ID fractional dose of ChAdOx1 nCoV-19 elicited higher effector CD8+ T cell responses than IM vaccination. This study confirmed that an ID dose-reduction vaccination strategy effectively stimulates effector memory T cell responses. ID injection could be an improved approach for effective vaccination programs.

A Phase I/II Clinical Trial of Intradermal, Controllable Self-Replicating Ribonucleic Acid Vaccine EXG-5003 against SARS-CoV-2

mRNA vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have played a key role in reducing morbidity and mortality from coronavirus disease 2019 (COVID-19). We conducted a double-blind, placebo-controlled phase I/II trial to evaluate the safety, tolerability, and immunogenicity of EXG-5003, a two-dose, controllable self-replicating RNA vaccine against SARS-CoV-2. EXG-5003 encodes the receptor binding domain (RBD) of SARS-CoV-2 and was administered intradermally without lipid nanoparticles (LNPs). The participants were followed for 12 months. Forty healthy participants were enrolled in Cohort 1 (5 µg per dose, n = 16; placebo, n = 4) and Cohort 2 (25 µg per dose, n = 16; placebo, n = 4). No safety concerns were observed with EXG-5003 administration. SARS-CoV-2 RBD antibody titers and neutralizing antibody titers were not elevated in either cohort. Elicitation of antigen-specific cellular immunity was observed in the EXG-5003 recipients in Cohort 2. At the 12-month follow-up, participants who had received an approved mRNA vaccine (BNT162b2 or mRNA-1273) >1 month after receiving the second dose of EXG-5003 showed higher cellular responses compared with equivalently vaccinated participants in the placebo group. The findings suggest a priming effect of EXG-5003 on the long-term cellular immunity of approved SARS-CoV-2 mRNA vaccines.

Long Term Assessment of Anti-SARS-CoV-2 Immunogenicity after mRNA Vaccine in Persons Living with HIV

(1) Background: Waning of neutralizing and cell-mediated immune response after the primary vaccine cycle (PVC) and the first booster dose (BD) is of concern, especially for PLWH with a CD4 count ≤200 cells/mm3. (2) Methods: Neutralizing antibodies (nAbs) titers by microneutralization assay against WD614G/Omicron BA.1 and IFNγ production by ELISA assay were measured in samples of PLWH at four time points [2 and 4 months post-PVC (T1 and T2), 2 weeks and 5 months after the BD (T3 and T4)]. Participants were stratified by CD4 count after PVC (LCD4, ≤200/mm3; ICD4, 201-500/mm3, and HCD4, >500/mm3). Mixed models were used to compare mean responses over T1-T4 across CD4 groups. (3) Results: 314 PLWH on ART (LCD4 = 56; ICD4 = 120; HCD4 = 138) were enrolled. At T2, levels of nAbs were significantly lower in LCD4 vs. ICD4/HCD4 (p = 0.04). The BD was crucial for increasing nAbs titers above 1:40 at T3 and up to T4 for WD614G. A positive T cell response after PVC was observed in all groups, regardless of CD4 (p = 0.31). (4) Conclusions: Waning of nAbs after PVC was more important in LCD4 group. The BD managed to re-establish higher levels of nAbs against WD614G, which were retained for 5 months, but for shorter time for Omicron BA.1. The T cellular response in the LCD4 group was lower than that seen in participants with higher CD4 count, but, importantly, it remained above detectable levels over the entire study period.

Both Humoral and Cellular Immune Responses to SARS-CoV-2 Are Essential to Prevent Infection: a Prospective Study in a Working Vaccinated Population from Southern France

COVID-19 vaccines have significantly decreased the number of severe cases of the disease, but the virus circulation remains important, and questions about the need of new vaccination campaigns remain unanswered. The individual's protection against SARS-CoV-2 infection is most commonly measured by the level and the neutralizing capacity of antibodies produced against SARS-CoV-2. T cell response is a major contributor in viral infection, and several studies have shown that cellular T cell response is crucial in fighting off SARS-CoV-2 infection. Actually, no threshold of protective immune response against SARS-CoV2 infection has been identified. To better understand SARS-CoV-2-mediated immunity, we assessed both B cell (measuring anti-Spike IgG titer and neutralization capacity) and T cell (measuring IFNγ release assay after specific SARS-CoV2 stimulation) responses to SARS-CoV-2 vaccination with or without virus encounter in a cohort of 367 working volunteers. Vaccinated individuals who had previously been infected had a stronger and more lasting immunity in comparison to vaccinated individuals naive to infection whose immunity started to decline 3 months after vaccination. IFNγ release ≥ 0.285 IU/mL and anti-Spike IgG antibodies ≥ 244 BAU/mL were associated with a sufficient immune response following vaccination preventing future infections. Individuals with comorbidities had a lower chance of reaching the protective thresholds of T cell and B cell responses as identified in multivariate analysis. A combined B cell and T cell analysis of immune responses to determine protective thresholds after SARS-CoV-2 vaccination will allow us to identify individuals in need of a booster vaccine dose, particularly in comorbid subjects.

Torquetenovirus Loads in Peripheral Blood Predict Both the Humoral and Cell-Mediated Responses to SARS-CoV-2 Elicited by the mRNA Vaccine in Liver Transplant Recipients

Three years into the COVID-19 pandemic, mass vaccination campaigns have largely controlled the disease burden but have not prevented virus circulation. Unfortunately, many immunocompromised patients have failed to mount protective immune responses after repeated vaccinations, and liver transplant recipients are no exception. Across different solid organ transplant populations, the plasma levels of Torquetenovirus (TTV), an orphan and ubiquitous human virus under control of the immune system, have been shown to predict the antibody response after COVID-19 vaccinations. We show here a single-institution experience with TTV viremia in 134 liver transplant recipients at their first or third dose. We found that TTV viremia before the first and third vaccine doses predicts serum anti-SARS-CoV-2 Spike receptor-binding domain (RBD) IgG levels measured 2-4 weeks after the second or third dose. Pre-vaccine TTV loads were also associated with peripheral blood anti-SARS-CoV-2 cell-mediated immunity but not with serum SARS-CoV-2 neutralizing antibody titers.

A Paratope-Enhanced Method to Determine Breadth and Depth TCR Clonal Metrics of the Private Human T-Cell Vaccine Response after SARS-CoV-2 Vaccination

Quantitative metrics for vaccine-induced T-cell responses are an important need for developing correlates of protection and their use in vaccine-based medical management and population health. Molecular TCR analysis is an appealing strategy but currently requires a targeted methodology involving complex integration of ex vivo data (antigen-specific functional T-cell cytokine responses and TCR molecular responses) that uncover only public antigen-specific metrics. Here, we describe an untargeted private TCR method that measures breadth and depth metrics of the T-cell response to vaccine challenge using a simple pre- and post-vaccine subject sampling, TCR immunoseq analysis, and a bioinformatic approach using self-organizing maps and GLIPH2. Among 515 subjects undergoing SARS-CoV-2 mRNA vaccination, we found that breadth and depth metrics were moderately correlated between the targeted public TCR response and untargeted private TCR response methods. The untargeted private TCR method was sufficiently sensitive to distinguish subgroups of potential clinical significance also observed using public TCR methods (the reduced T-cell vaccine response with age and the paradoxically elevated T-cell vaccine response of patients on anti-TNF immunotherapy). These observations suggest the promise of this untargeted private TCR method to produce T-cell vaccine-response metrics in an antigen-agnostic and individual-autonomous context.

Six-month immune responses to mRNA-1273 vaccine in combination antiretroviral therapy treated late presenter people with HIV according to previous SARS-CoV-2 infection

OBJECTIVE

Immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in people with HIV (PWH) with a history of late presentation (LP) and their durability have not been fully characterized.

DESIGN

In this prospective, longitudinal study, we sought to assess T-cell and humoral responses to SARS-CoV-2 mRNA vaccination up to 6 months in LP-PWH on effective combination antiretroviral therapy (cART) as compared to HIV-negative healthcare workers (HCWs), and to evaluate whether previous SARS-CoV-2 infection modulates immune responses to vaccine.

METHODS

SARS-CoV-2 spike (S)-specific T-cell responses were determined by two complementary flow cytometry methodologies, namely activation-induced marker (AIM) assay and intracellular cytokine staining (ICS), whereas humoral responses were measured by ELISA [anti-receptor binding domain (RBD) antibodies) and receptor-binding inhibition assay (spike-ACE2 binding inhibition activity), before vaccination (T0), 1 month (T1) and 5 months (T2) after the second dose.

RESULTS

LP-PWH showed at T1 and T2 significant increase of: S-specific memory and circulating T follicular helper (cTfh) CD4 + T cells; polyfunctional Th1-cytokine (IFN-γ, TNF-α, IL-2)- and Th2-cytokine (IL-4)-producing S-specific CD4 + T cells; anti-RBD antibodies and spike-ACE2 binding inhibition activity. Immune responses to vaccine in LP-PWH were not inferior to HCWs overall, yet S-specific CD8 + T cells and spike-ACE2 binding inhibition activity correlated negatively with markers of immune recovery on cART. Interestingly, natural SARS-CoV-2 infection, while able to sustain S-specific antibody response, seems less efficacious in inducing a T-cell memory and in boosting immune responses to vaccine, possibly reflecting an enduring partial immunodeficiency.

CONCLUSIONS

Altogether, these findings support the need for additional vaccine doses in PWH with a history of advanced immune depression and poor immune recovery on effective cART.

Auto-immunoproteomics analysis of COVID-19 ICU patients revealed increased levels of autoantibodies related to the male reproductive system

Background: Coronavirus disease (COVID-19) manifests many clinical symptoms, including an exacerbated immune response and cytokine storm. Autoantibodies in COVID-19 may have severe prodromal effects that are poorly understood. The interaction between these autoantibodies and self-antigens can result in systemic inflammation and organ dysfunction. However, the role of autoantibodies in COVID-19 complications has yet to be fully understood. Methods: The current investigation screened two independent cohorts of 97 COVID-19 patients [discovery (Disc) cohort from Qatar (case = 49 vs. control = 48) and replication (Rep) cohort from New York (case = 48 vs. control = 28)] utilizing high-throughput KoRectly Expressed (KREX) Immunome protein-array technology. Total IgG autoantibody responses were evaluated against 1,318 correctly folded and full-length human proteins. Samples were randomly applied on the precoated microarray slides for 2 h. Cy3-labeled secondary antibodies were used to detect IgG autoantibody response. Slides were scanned at a fixed gain setting using the Agilent fluorescence microarray scanner, generating a 16-bit TIFF file. Group comparisons were performed using a linear model and Fisher's exact test. Differentially expressed proteins were used for KEGG and WIKIpathway annotation to determine pathways in which the proteins of interest were significantly over-represented. Results and conclusion: Autoantibody responses to 57 proteins were significantly altered in the COVID-19 Disc cohort compared to healthy controls (p ≤ 0.05). The Rep cohort had altered autoantibody responses against 26 proteins compared to non-COVID-19 ICU patients who served as controls. Both cohorts showed substantial similarities (r 2 = 0.73) and exhibited higher autoantibody responses to numerous transcription factors, immunomodulatory proteins, and human disease markers. Analysis of the combined cohorts revealed elevated autoantibody responses against SPANXN4, STK25, ATF4, PRKD2, and CHMP3 proteins in COVID-19 patients. The sequences for SPANXN4 and STK25 were cross-validated using sequence alignment tools. ELISA and Western blot further verified the autoantigen-autoantibody response of SPANXN4. SPANXN4 is essential for spermiogenesis and male fertility, which may predict a potential role for this protein in COVID-19-associated male reproductive tract complications, and warrants further research.

SARS-CoV-2 T Cell Immunity Responses following Natural Infection and Vaccination

(1) Background: SARS-CoV-2 T cell immunity is rapidly activated following SARS-CoV-2 infection and vaccination and is crucial for controlling infection progression and severity. The aim of the present study was to compare the levels of T cell responses to SARS-CoV-2 between cohorts of subjects with hybrid immunity (convalescent and vaccinated), vaccinated naïve (non-exposed) and convalescent unvaccinated subjects. (2) Methods: We performed a retrospective descriptive analysis of data collected from the medical records of adult individuals who were consecutively examined at a large, private Medical Center of Attica from September 2021 to September 2022 in order to be examined on their own initiative for SARS-CoV-2 T cell immunity response. They were divided into three groups: Group A: SARS-CoV-2 convalescent and vaccinated subjects; Group B: SARS-CoV-2 naïve vaccinated subjects; Group C: SARS-CoV-2 convalescent unvaccinated subjects. The SARS-CoV-2 T cell response was estimated against spike (S) and nucleocapsid (N) structural proteins by performing the methodology T-SPOT.COVID test. (3) Results: A total of 530 subjects were retrospectively included in the study, 252 females (47.5%) and 278 (52.5%) males ranging from 13 to 92 years old (mean 55.68 ± 17.0 years). Among them, 66 (12.5%) were included in Group A, 284 (53.6%) in Group B and 180 (34.0%) in Group C. Among the three groups, a reaction against S antigen was reported in 58/66 (87.8%) of Group A, 175/284 (61.6%) of Group B and 146/180 (81.1%) of Group C (chi-square, p < 0.001). Reaction against N antigen was present in 49/66 (74.2%) of Group A and in 140/180 (77.7%) of Group C (chi-square, p = 0.841). The median SFC count for S antigen was 24 (range from 0-218) in Group A, 12 (range from 0-275) in Group B and 18 (range from 0-160) in Group C (Kruskal-Wallis test, p < 0.001; pairwise comparisons: groups A-B, p < 0.001; groups A-C, p = 0.147; groups B-C, p < 0.001). The median SFCs count for N antigen was 13 (range 0-82) for Group A and 18 (range 0-168) for Group C (Kruskal-Wallis test, p = 0.27 for A-C groups). (4) Conclusions: Our findings suggest that natural cellular immunity, either alone or combined with vaccination, confers stronger and more durable protection compared to vaccine-induced cellular immunity.

Humoral and cell-mediated immune responses to BNT162b2 vaccine against SARS-CoV-2 in people with cystic fibrosis

People with cystic fibrosis (pwCF) were considered to be clinically vulnerable to COVID-19 and were therefore given priority in the vaccination campaign. Vaccines induced a humoral response in these patients that was comparable to the response observed among the general population. However, the role of the cell-mediated immune response in providing long-term protection against SARS-CoV-2 in pwCF has not yet been defined. In this study, humoral (antibody titre) and cell-mediated immune responses (interferon-γ release) to the BNT162b2 vaccine were measured at different time points, from around 6-8 months after the 2nd dose and up to 8 months after the 3rd dose, in 118 CF patients and 26 non-CF subjects. Subjects were sampled between November 2021 and September 2022 and followed-up for breakthrough infection through October 2022. pwCF mounted a cell-mediated response that was similar to that observed in non-CF subjects. Low antibody titres (<1st quartile) were associated with a higher risk of breakthrough infection (HR: 2.39, 95 % CI: 1.17-4.88), while there was no significant association with low INF-γ levels (<0.3 IU/mL) (HR: 1.38, 95 % CI: 0.64-2.99). Further studies are needed in subgroup of pwCF receiving immunosuppressive therapy, such as organ transplant recipients. This data is important for tailoring vaccination strategies for this clinically vulnerable population.

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.

Hybrid immunity expands the functional humoral footprint of both mRNA and vector-based SARS-CoV-2 vaccines

Despite the successes of current coronavirus disease 2019 (COVID-19) vaccines, waning immunity, the emergence of variants of concern, and breakthrough infections among vaccinees have begun to highlight opportunities to improve vaccine platforms. Real-world vaccine efficacy studies have highlighted the reduced risk of breakthrough infections and diseases among individuals infected and vaccinated, referred to as hybrid immunity. Thus, we sought to define whether hybrid immunity shapes the humoral immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) following Pfizer/BNT162b2, Moderna mRNA-1273, ChadOx1/AZD1222, and Ad26.COV2.S vaccination. Each vaccine exhibits a unique functional humoral profile in vaccination only or hybrid immunity. However, hybrid immunity shows a unique augmentation of S2-domain-specific functional immunity that was poorly induced for the vaccination only. These data highlight the importance of natural infection in breaking the immunodominance away from the evolutionarily unstable S1 domain and potentially affording enhanced cross-variant protection by targeting the more highly conserved S2 domain of SARS-CoV-2.

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-β-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 (T_EM) cells, independently of the stimulus suggesting the association of this phenotype with MS status. CD4⁺ and CD8⁺ T_EM cell frequency was further increased at T3 compared with T2.

CONCLUSIONS

COVID-19 vaccine booster strengthens humoral and Th1-cell responses and increases T_EM cells in PwMS.

Immunologic Interplay Between HIV/AIDS and COVID-19: Adding Fuel to the Flames?

PURPOSE OF REVIEW

HIV/AIDS and COVID-19 have been the major pandemics overwhelming our times. Given the enduring immune disfunction featuring people living with HIV (PLWH) despite combination antiretroviral therapy (cART), concerns for higher incidence and severity of SARS-CoV-2 infection as well as for suboptimal responses to the newly developed vaccines in this population arose early during the pandemics. Herein, we discuss the complex interplay between HIV and SARS-CoV-2, with a special focus on the immune responses to SARS-CoV-2 natural infection and vaccination in PLWH.

RECENT FINDINGS

Overall, current literature shows that COVID-19 severity and outcomes may be worse and immune responses to infection or vaccination lower in PLWH with poor CD4 + T-cell counts and/or uncontrolled HIV viremia. Data regarding the risk of post-acute sequelae of SARS-CoV-2 infection (PASC) among PLWH are extremely scarce, yet they seem to suggest a higher incidence of such condition. Scarce immunovirological control appears to be the major driver of weak immune responses to SARS-CoV-2 infection/vaccination and worse COVID-19 outcomes in PLWH. Therefore, such individuals should be prioritized for vaccination and should receive additional vaccine doses. Furthermore, given the potentially higher risk of developing long-term sequelae, PLWH who experienced COVID-19 should be ensured a more careful and prolonged follow-up.

A longitudinal analysis of humoral, T cellular response and influencing factors in a cohort of healthcare workers: Implications for personalized SARS-CoV-2 vaccination strategies

Introduction

SARS-CoV-2 mRNA vaccinations elicit both virus-specific humoral and T-cell responses, but a complex interplay of different influencing factors, such as natural immunity, gender, and age, guarantees host protection. The present study aims to assess the immune dynamics of humoral, T-cell response, and influencing factors to stratify individual immunization status up to 10 months after Comirnaty-vaccine administration.

Methods

To this aim, we longitudinally evaluated the magnitude and kinetics of both humoral and T-cell responses by serological tests and enzyme-linked immunospot assay at 5 time points. Furthermore, we compared the course over time of the two branches of adaptive immunity to establish an eventual correlation between adaptive responses. Lastly, we evaluated putative influencing factors collected by an anonymized survey administered to all participants through multiparametric analysis. Among 984 healthcare workers evaluated for humoral immunity, 107 individuals were further analyzed to describe SARS-CoV-2-specific T-cell responses. Participants were divided into 4 age groups: &lt;40 and ≥40 years for men, &lt;48 and ≥48 years for women. Furthermore, results were segregated according to SARS-CoV-2-specific serostatus at baseline.

Results

The disaggregated evaluation of humoral responses highlighted antibody levels decreased in older subjects. The humoral responses were higher in females than in males (p=0.002) and previously virus-exposed subjects compared to naïve subjects (p&lt;0.001). The vaccination induced a robust SARS-CoV-2 specific T-cell response at early time points in seronegative subjects compared to baseline levels (p&lt;0.0001). However, a contraction was observed 6 months after vaccination in this group (p&lt;0.01). On the other hand, the pre-existing specific T-cell response detected in natural seropositive individuals was longer-lasting than the response of the seronegative subjects, decreasing only 10 months after vaccination. Our data suggest that T-cell reactiveness is poorly impacted by sex and age. Of note, SARS-CoV-2-specific T-cell response was not correlated to the humoral response at any time point.

Discussion

These findings suggest prospects for rescheduling vaccination strategies by considering individual immunization status, personal characteristics, and the appropriate laboratory tests to portray immunity against SARS-CoV-2 accurately. Deepening our knowledge about T and B cell dynamics might optimize the decision-making process in vaccination campaigns, tailoring it to each specific immune response.

Detailed characterization of SARS-CoV-2-specific T and B cells after infection or heterologous vaccination

The formation of a robust long-term antigen (Ag)-specific memory, both humoral and cell-mediated, is created following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or vaccination. Here, by using polychromatic flow cytometry and complex data analyses, we deeply investigated the magnitude, phenotype, and functionality of SARS-CoV-2-specific immune memory in two groups of healthy subjects after heterologous vaccination compared to a group of subjects who recovered from SARS-CoV-2 infection. We find that coronavirus disease 2019 (COVID-19) recovered patients show different long-term immunological profiles compared to those of donors who had been vaccinated with three doses. Vaccinated individuals display a skewed T helper (Th)1 Ag-specific T cell polarization and a higher percentage of Ag-specific and activated memory B cells expressing immunoglobulin (Ig)G compared to those of patients who recovered from severe COVID-19. Different polyfunctional properties characterize the two groups: recovered individuals show higher percentages of CD4+ T cells producing one or two cytokines simultaneously, while the vaccinated are distinguished by highly polyfunctional populations able to release four molecules, namely, CD107a, interferon (IFN)-γ, tumor necrosis factor (TNF), and interleukin (IL)-2. These data suggest that functional and phenotypic properties of SARS-CoV-2 adaptive immunity differ in recovered COVID-19 individuals and vaccinated ones.

SARS-CoV-2 Antibody Dynamics in Healthcare Workers after mRNA Vaccination

Since the emergence of SARS-CoV-2, maintaining healthcare worker (HCW) health and safety has been fundamental to responding to the global pandemic. Vaccination with mRNA-base vaccines targeting SARS-CoV-2 spike protein has emerged as a key strategy in reducing HCW susceptibility to SARS-CoV-2, however, neutralizing antibody responses subside with time and may be influenced by many variables. We sought to understand the dynamics between vaccine products, prior clinical illness from SARS-CoV-2, and incidence of vaccine-associated adverse reactions on antibody decay over time in HCWs at a university medical center. A cohort of 296 HCWs received standard two-dose vaccination with either bnt162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) and were evaluated after two, six, and nine months. Subjects were grouped by antibody decay curve into steep antibody decliners gentle decliners. Vaccination with mRNA-1273 led to more sustained antibody responses compared to bnt162b2. Subjects experiencing vaccine-associated symptoms were more likely to experience a more prolonged neutralizing antibody response. Subjects with clinical SARS-CoV-2 infection prior to vaccination were more likely to experience vaccination-associated symptoms after first vaccination and were more likely to have a more blunted antibody decay. Understanding factors associated with vaccine efficacy may assist clinicians in determining appropriate vaccine strategies in HCWs.

Persistence of spike-specific immune responses in BNT162b2-vaccinated donors and generation of rapid ex-vivo T cells expansion protocol for adoptive immunotherapy: A pilot study

Introduction

The BNT162b2 mRNA-based vaccine has shown high efficacy in preventing COVID-19 infection but there are limited data on the types and persistence of the humoral and T cell responses to such a vaccine.

Methods

Here, we dissect the vaccine-induced humoral and cellular responses in a cohort of six healthy recipients of two doses of this vaccine.

Results and discussion

Overall, there was heterogeneity in the spike-specific humoral and cellular responses among vaccinated individuals. Interestingly, we demonstrated that anti-spike antibody levels detected by a novel simple automated assay (Jess) were strongly correlated (r=0.863, P<0.0001) with neutralizing activity; thus, providing a potential surrogate for neutralizing cell-based assays. The spike-specific T cell response was measured with a newly modified T-spot assay in which the high-homology peptide-sequences cross-reactive with other coronaviruses were removed. This response was induced in 4/6 participants after the first dose, and all six participants after the second dose, and remained detectable in 4/6 participants five months post-vaccination. We have also shown for the first time, that BNT162b2 vaccine enhanced T cell responses also against known human common viruses. In addition, we demonstrated the efficacy of a rapid ex-vivo T cell expansion protocol for spike-specific T cell expansion to be potentially used for adoptive-cell therapy in severe COVID-19, immunocompromised individuals, and other high-risk groups. There was a 9 to 13.7-fold increase in the number of expanded T cells with a significant increase of anti-spike specific response showing higher frequencies of both activation and cytotoxic markers. Interestingly, effector memory T cells were dominant in all four participants' CD8+ expanded memory T cells; CD4+ T cells were dominated by effector memory in 2/4 participants and by central memory in the remaining two participants. Moreover, we found that high frequencies of CD4+ terminally differentiated memory T cells were associated with a greater reduction of spike-specific activated CD4+ T cells. Finally, we showed that participants who had a CD4+ central memory T cell dominance expressed a high CD69 activation marker in the CD4+ activated T cells.

Persistent T cell-mediated immune responses against Omicron variants after the third COVID-19 mRNA vaccine dose

Introduction

The prime-boost COVID-19 mRNA vaccination strategy has proven to be effective against severe COVID-19 disease and death. However, concerns have been raised due to decreasing neutralizing antibody levels after COVID-19 vaccination and due to the emergence of new immuno-evasive SARS-CoV-2 variants that may require additional booster vaccinations.

Methods

In this study, we analyzed the humoral and cell-mediated immune responses against the Omicron BA.1 and BA.2 subvariants in Finnish healthcare workers (HCWs) vaccinated with three doses of COVID-19 mRNA vaccines. We used enzyme immunoassay and microneutralization test to analyze the levels of SARS-CoV-2 specific IgG antibodies in the sera of the vaccinees and the in vitro neutralization capacity of the sera. Activation induced marker assay together with flow cytometry and extracellular cytokine analysis was used to determine responses in SARS-CoV-2 spike protein stimulated PBMCs.

Results

Here we show that within the HCWs, the third mRNA vaccine dose recalls both humoral and T cell-mediated immune responses and induces high levels of neutralizing antibodies against Omicron BA.1 and BA.2 variants. Three weeks after the third vaccine dose, SARS-CoV-2 wild type spike protein-specific CD4⁺ and CD8⁺ T cells are observed in 82% and 71% of HCWs, respectively, and the T cells cross-recognize both Omicron BA.1 and BA.2 spike peptides. Although the levels of neutralizing antibodies against Omicron BA.1 and BA.2 decline 2.5 to 3.8-fold three months after the third dose, memory CD4⁺ T cell responses are maintained for at least eight months post the second dose and three months post the third vaccine dose.

Discussion

We show that after the administration of the third mRNA vaccine dose the levels of both humoral and cell-mediated immune responses are effectively activated, and the levels of the spike-specific antibodies are further elevated compared to the levels after the second vaccine dose. Even though at three months after the third vaccine dose antibody levels in sera decrease at a similar rate as after the second vaccine dose, the levels of spike-specific CD4⁺ and CD8⁺ T cells remain relatively stable. Additionally, the T cells retain efficiency in cross-recognizing spike protein peptide pools derived from Omicron BA.1 and BA.2 subvariants. Altogether our results suggest durable cellmediated immunity and protection against SARS-CoV-2.

Long-term adaptive response in COVID-19 vaccine recipients and the effect of a booster dose

We examined the immune response in subjects previously infected with SARS-CoV2 and infection-naïve 9 months after primary 2-dose COVID-19 mRNA vaccination and 3 months after the booster dose in a longitudinal cohort of healthcare workers. Nine months after primary vaccination, previously infected subjects exhibited higher residual antibody levels, with significant neutralizing activity against distinct variants compared to infection-naïve subjects. The higher humoral response was associated with higher levels of receptor binding domain (RBD)-specific IgG⁺ and IgA⁺ memory B cells. The booster dose increased neither neutralizing activity, nor the B and T cell frequencies. Conversely, infection-naïve subjects needed the booster to achieve comparable levels of neutralizing antibodies as those found in previously infected subjects after primary vaccination. The neutralizing titer correlated with anti-RBD IFNγ producing T cells, in the face of sustained B cell response. Notably, pre-pandemic samples showed high Omicron cross-reactivity. These data show the importance of the booster dose in reinforcing immunological memory and increasing circulating antibodies in infection-naïve subjects.

Immunogenicity of a Fractional Dose of mRNA BNT162b2 COVID-19 Vaccine for Primary Series and Booster Vaccination among Healthy Adolescents

Primary series vaccination with BNT162b2 followed by a booster 5 months later has been recommended for healthy adolescents. We aimed to describe the immunogenicity in a fractional dose of BNT162b2. Adolescents aged 12–18 years were randomized into six arms for primary series administration: 3wPZ30/30 (reference group), 3wPZ30/20, 3wPZ20/20, 6wPZ30/30, 6wPZ30/20, and 6wPZ20/20 μg. A booster was given at 5 months after the second dose using either 10 or 15 μg of BNT162b2. Immunogenicity following vaccination was determined by IgG against receptor-binding domain (anti-S-RBD IgG; BAU/mL), surrogate virus neutralization test (sVNT; %inhibition) and pseudovirus neutralization (pVNT;ID₅₀) against Omicron. Non-inferiority criteria were defined as a lower boundary of the geometric mean ratio (GMR) being greater than 0.67. From September to October 2021, 118 adolescents with a median age (IQR) of 14.9 years (13.9–16.7) were enrolled. Fourteen days after the primary series, the geometric means (GMs) of anti-S-RBD IgG (BAU/mL) were 3090 (95% CI 2761–3460) in 3wPZ30/30. The GMRs of anti-S-RBD were: 0.80 (95% CI 0.67–0.97) in 3wPZ30/20; 1.00 (95% CI 0.83–1.20) in 3wPZ20/20; 1.37 (95% CI 1.13–1.65) in 6wPZ30/30; 1.24 (95% CI 1.02–1.50) in 6wPZ30/20; and 1.36 (1.13–1.64) in 6wPZ20/20. After a booster dose with 15 μg (n = 24) of BNT162b2, sVNT and pVNT against Omicron variant were 91.6 (95% CI 88.4–94.9) and 331 (95% CI 221–495), respectively. In the group that received 10 μg of BNT162b2 (n = 25), sVNT was 85.6 (95% CI 80.0–91.6) and pVNT was 397 (95% CI 267–590). Healthy adolescents had good immune responses to the fractional dose regimen of BNT162b2 and this may be considered as an alternative option.

Lymphocyte Subpopulations Associated with Neutralizing Antibody Levels of SARS-CoV-2 for COVID-19 Vaccination

The comprehensive knowledge regarding the immune response during coronavirus disease 2019 (COVID-19) vaccination is limited. The aim of this study was to longitudinally investigate not only the dynamic changes of peripheral lymphocyte subpopulations and cytokine levels but parallel changes of antibody levels against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Blood samples of 20 healthcare workers with two doses of COVID-19 vaccine were prospectively collected. The percentages of lymphocyte subpopulations from peripheral blood and cytokine production in lymphocytes with in vitro stimulation were assessed using eight-color flow cytometry. SARS-CoV-2 spike antibodies (anti-S Abs) and functional neutralizing antibodies (nAbs) were also measured. The relation between pre- and post-vaccination immunity was analyzed. There are 7 men and 13 women with a median age of 44.0 years (range: 25.7−59.5 years). The individuals had an increased percentage of lymphocytes at post-vaccination with statistical significance post first dose (p = 0.031). The levels of transitional cells (p = 0.001), such as plasmablasts (p < 0.001) and plasma cells (p = 0.031), were increased compared with pre-vaccination. Recent thymic emigrants of CD4+ T cells subsets were significantly higher at post-vaccination than those at pre-vaccination (p = 0.029). Intracellular levels of tumor necrosis factor-alpha, interferon-γ, interleukin (IL)-2, IL-21, transforming growth factor-beta and IL-17 produced by CD4+ T, CD8+ T, and natural killer cells were increased. All individual samples showed reactivity to anti-S Abs and the levels of nAbs were elevated after vaccination. The magnitude of adaptive immunity was associated with vaccine types and doses. Alterations of total memory B cells (p < 0.001), non-switched memory B cells (p = 0.016), and memory Treg cells (p < 0.001) were independent predictors for nAb levels. These findings might be helpful in elucidating the immune response of COVID-19 vaccination and in developing new strategies for immunization.

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.