Cellular and Humoral Immune Responses and Breakthrough Infections After Two Doses of BNT162b Vaccine in Healthcare Workers (HW) 180 Days After the Second Vaccine Dose

Immunogenicity and safety of COVID-19 booster vaccination: A population-based clinical trial to identify the best vaccination strategy

BACKGROUND

Various SARS-CoV-2 variants of concerns (VOCs) characterized by higher transmissibility and immune evasion have emerged. Despite reduced vaccine efficacy against VOCs, currently available vaccines provide protection. Population-based evidence on the humoral immune response after booster vaccination is crucial to guide future vaccination strategies and in preparation for imminent COVID-19 waves.

METHODS

This multicenter, population-based cohort study included 4697 individuals ≥18 years of age who received a booster vaccination. Antibody levels against SARS-CoV-2 receptor binding domain (RBD) and neutralizing antibodies against wild-type (WT) virus and Omicron variants were assessed at baseline (day of booster vaccination) and after four weeks. Safety was evaluated daily within the first week using a participant-completed electronic diary. Antibody levels were compared across different vaccination strategies, taking into account individual host factors.

RESULTS

Our main model including 3838 participants revealed that individuals who received a booster with mRNA-1273 compared to BNT162b2 vaccine had a significantly higher increase (95 %CI) in anti-RBD-antibody levels (37,707 BAU/mL [34,575-40,839] vs. 27,176 BAU/mL [26,265-28,087]), and of neutralization levels against WT (1,681 [1490-1872] vs. 1141 [1004-1278] and Omicron variant (422 [369-474] vs. 329 [284-374]). Neutralizing antibody titres highly correlated with anti-RBD antibodies, with neutralizing capacity 4.4 fold higher against WT compared to Omicron. No differences in safety were found between the two booster vaccines.

CONCLUSION

Our study underlines the superiority of a booster vaccination with mRNA-1273, independent of the primary vaccination and therefore provides guidance on the vaccination strategy.

Impact of methotrexate on humoral and cellular immune responses to SARS-CoV-2 mRNA vaccine in patients with rheumatoid arthritis

The aim of this study was to longitudinally evaluate the undetermined impact of methotrexate (MTX) on the cumulative immunogenicity elicited by three doses of SARS-CoV-2 mRNA vaccination in patients with rheumatoid arthritis (RA). We prospectively evaluated vaccine-induced immune responses following the first dose, 1 and 6 months after the second dose, and 1 month after the third dose of BNT162b2 or mRNA-1273 in 144 SARS-CoV-2 naïve participants (70 patients with RA, 29 disease controls without immunosuppressive conditions, and 45 healthy controls). Humoral immune responses were assessed by quantifying anti-spike IgG antibody titers and the capacity of circulating antibodies to neutralize the ancestral SARS-CoV-2 strain and the Alpha, Delta, and Omicron variants. Vaccine-induced T-cell responses were measured using an interferon-gamma release assay. At 1 and 6 months after the second dose, anti-spike titers were highest in healthy controls, followed by disease controls and patients with RA. Multivariate analyses revealed that MTX treatment was significantly associated with a decrease in anti-spike titers, neutralizing activity, and SARS-CoV-2-specific interferon-gamma levels. Furthermore, MTX dose per body weight was negatively correlated with these two indices of humoral immune response. The third vaccine dose boosted anti-spike titers, especially in patients receiving MTX, while sera from these patients neutralized the Omicron variant far less robustly than those from healthy controls. In conclusion, MTX attenuated immunogenicity following two doses of SARS-CoV-2 mRNA vaccine in patients with RA, particularly resulting in dose-dependent suppression of the humoral immune response. Furthermore, MTX deteriorated the neutralizing activity against the Omicron variant, even after the third immunization.

Longitudinal Analysis of SARS-CoV-2-Specific Cellular and Humoral Immune Responses and Breakthrough Infection following BNT162b2/BNT162b2/BNT162b2 and ChAdOx1/ChAdOx1/BNT162b2 Vaccination: A Prospective Cohort in Naive Healthcare Workers

Assessing immune responses post-SARS-CoV-2 vaccination is crucial for optimizing vaccine strategies. This prospective study aims to evaluate immune responses and breakthrough infection in 235 infection-naïve healthcare workers up to 13-15 months after initial vaccination in two vaccine groups (108 BNT/BNT/BNT and 127 ChAd/ChAd/BNT). Immune responses were assessed using the interferon-gamma enzyme-linked immunospot (ELISPOT) assay, total immunoglobulin, and neutralizing activity through surrogate virus neutralization test at nine different time points. Both groups exhibited peak responses one to two months after the second or third dose, followed by gradual declines over six months. Notably, the ChAd group exhibited a gradual increase in ELISPOT results, but their antibody levels declined more rapidly after reaching peak response compared to the BNT group. Six months after the third dose, both groups had substantial cellular responses, with superior humoral responses in the BNT group (p < 0.05). As many as 55 breakthrough infection participants displayed higher neutralization activities against Omicron variants, but similar cellular responses compared to 127 infection-naïve individuals, suggesting cross-immunity. Distinct neutralization classifications (<30%, >80% inhibition) correlated with different ELISPOT results. Our study reveals diverse immune response patterns based on vaccine strategies and breakthrough infections, emphasizing the importance of understanding these dynamics for optimized vaccination decisions.

Waning cellular immune responses and predictive factors in maintaining cellular immunity against SARS-CoV-2 six months after BNT162b2 mRNA vaccination

Several clinical trials have shown that the humoral response produced by anti-spike antibodies elicited by coronavirus disease 2019 (COVID-19) vaccines gradually declines. The kinetics, durability and influence of epidemiological and clinical factors on cellular immunity have not been fully elucidated. We analyzed cellular immune responses elicited by BNT162b2 mRNA vaccines in 321 health care workers using whole blood interferon-gamma (IFN-γ) release assays. IFN-γ, induced by CD4 + and CD8 + T cells stimulated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike epitopes (Ag2), levels were highest at 3 weeks after the second vaccination (6 W) and decreased by 37.4% at 3 months (4 M) and 60.0% at 6 months (7 M), the decline of which seemed slower than that of anti-spike antibody levels. Multiple regression analysis revealed that the levels of IFN-γ induced by Ag2 at 7 M were significantly correlated with age, dyslipidemia, focal adverse reactions to full vaccination, lymphocyte and monocyte counts in whole blood, Ag2 levels before the second vaccination, and Ag2 levels at 6 W. We clarified the dynamics and predictive factors for the long-lasting effects of cellular immune responses. The results emphasize the need for a booster vaccine from the perspective of SARS-CoV-2 vaccine-elicited cellular immunity.

Timing and implications for immune response to vaccine in SARS-CoV-2 breakthrough infections

COVID-19 vaccines elicit a strong anti-S antibodies response. We aim to describe antibody titers in peri-vaccination SARS-CoV-2 infections. This is a retrospective longitudinal single-cohort study. Serological tests were performed at the time of the first SARS-CoV-2 vaccine dose (T0) and 60 (T1), 120 (T2), and 240 (T3) days after. The study included 4,682 subjects. Group A had the infection without an anti-S Ig response. Group B and C seroconverted for anti-N Ig between T0 and T1 and between T1 and T2, respectively. Group D was persistently anti-N Ig negative. Group B showed an initial sub-optimal response, reaching the highest titer at T3. Those who received the second dose 120 days after the infection had higher titers compared to those who received it 21 days after the first dose. The immune response depends on the number and the timing of vaccine doses, highlighting the need for a more personalized approach to vaccination.

Long-term transition of antibody titers in healthcare workers following the first to fourth doses of mRNA COVID-19 vaccine: Comparison of two automated SARS-CoV-2 immunoassays

Anti-spike receptor binding domain (S-RBD) antibody against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which best correlates with virus-neutralizing antibody is useful for estimating the period of protection and identifying the timing of additional booster doses. Long-term transition of the S-RBD antibody titer and the antibody responses among healthy individuals remain unclear. In the present study, therefore, we monitored the S-RBD antibody titers of 16 healthcare workers every 4 weeks for 76 weeks after vaccination with a fourth dose of mRNA-1273 (Moderna) following three doses of BNT162b2 (Pfizer/BioNTech) using two commercial automated immunoassays (Roche and Abbott). Two antibody responses to the vaccine were similar with an up-down change before and after the second (weeks 3), third (weeks 40) and fourth (week 72) vaccinations, but the titer did not fall below the assay's positivity threshold in any individual. The peak level of the geometric mean titer (GMT) in the Roche assay was highest after the third vaccination, and that in Abbott assay was highest after the fourth vaccination but almost equal to that after the third vaccination. Both the geometric mean fold rise (GMFR) demonstrated by the Roche and Abbott assays were highest after the third vaccination. Antibody titers determined by the Roche and Abbott assays showed a positive strong correlation (correlation coefficient: 0.70 to 0.99), but the ratio (Roche/Abbott) of antibodies demonstrated by both assays increased 0.46- to 8.26-fold between weeks 3 and 76. These findings will be helpful for clinicians when interpreting results for SARS-CoV-2 antibody levels and considering future vaccination strategies.

Age and Cytokine Gene Variants Modulate the Immunogenicity and Protective Effect of SARS-CoV-2 mRNA-Based Vaccination

The introduction of anti-SARS-CoV-2 vaccines in late 2020 substantially changed the pandemic picture, inducing effective protection in the population. However, individual variability was observed with different levels of cellular response and neutralizing antibodies. We report data on the impact of age, gender, and 16 single nucleotide polymorphisms (SNPs) of cytokine genes on the anti-SARS-CoV-2 IgG titers measured 31 and 105 days after administration of the second dose of BNT162b2 vaccine to 122 healthy subjects from the health care staff of the Palermo University Hospital, Italy. The higher titers at 31 days were measured in the younger subjects and in subjects bearing T-positive genotypes of IL-1R1 rs2234650 or the GG homozygous genotype of IL-6 rs1800795 SNP. T-positive genotypes are also significantly more common in subjects with higher titers at day 105. In addition, in this group of subjects, the frequency of the CT genotype of IL-4 rs2243250 is higher among those vaccinated with higher titers. Moreover, these SNPs and TNFA rs1800629 are differently distributed in a group of subjects that were found infected by SARS-CoV-2 at day 105 of evaluation. Finally, subjects that were found to be infected by SARS-CoV-2 at day 105 were significantly older than the uninfected subjects. Taken together, these data seem to suggest that age and polymorphisms of key cytokines, which regulate inflammation and humoral immune response, might influence the magnitude of the antibody response to vaccination with BNT162B2, prompting speculation about the possible benefit of a genetic background-based assessment of a personalized approach to the anti-COVID vaccination schedule.

Cellular and humoral immune responses and breakthrough infections after three SARS-CoV-2 mRNA vaccine doses

Background

SARS-CoV-2 vaccination has proven the most effective measure to control the COVID-19 pandemic. Booster doses are being administered with limited knowledge on their need and effect on immunity.

Objective

To determine the duration of specific T cells, antibodies and neutralization after 2-dose vaccination, to assess the effect of a third dose on adaptive immunity and to explore correlates of protection against breakthrough infection.

Methods

12-month longitudinal assessment of SARS-CoV-2-specific T cells, IgG and neutralizing antibodies triggered by 2 BNT162b2 doses followed by a third mRNA-1273 dose in a cohort of 77 healthcare workers: 17 with SARS-CoV-2 infection prior to vaccination (recovered) and 60 naïve.

Results

Peak levels of cellular and humoral response were achieved 2 weeks after the second dose. Antibodies declined thereafter while T cells reached a plateau 3 months after vaccination. The decline in neutralization was specially marked in naïve individuals and it was this group who benefited most from the third dose, which resulted in a 20.9-fold increase in neutralization. Overall, recovered individuals maintained higher levels of T cells, antibodies and neutralization 1 to 6 months post-vaccination than naïve. Seventeen asymptomatic or mild SARS-CoV-2 breakthrough infections were reported during follow-up, only in naïve individuals. This viral exposure boosted adaptive immunity. High peak levels of T cells and neutralizing antibodies 15 days post-vaccination associated with protection from breakthrough infections.

Conclusion

Booster vaccination in naïve individuals and the inclusion of viral antigens other than spike in future vaccine formulations could be useful strategies to prevent SARS-CoV-2 breakthrough infections.

Effectiveness of Booster Dose of Anti SARS-CoV-2 BNT162b2 in Cirrhosis: Longitudinal Evaluation of Humoral and Cellular Response

Background: LC has been associated with hyporesponsiveness to several vaccines. Nonetheless, no data on complete serological and B- and T-cell immune response are currently available. Aims: To assess, in comparison with healthy controls of the same age and gender, both humoral and cellular immunoresponses of patients with LC after two or three doses of the mRNA Pfizer-BioNTech vaccine against SARS-CoV-2 and to investigate clinical features associated with non-response. Material and methods: 179 patients with LC of CTP class A in 93.3% and viral etiology in 70.1% of cases were longitudinally evaluated starting from the day before the first dose to 4 weeks after the booster dose. Their antibody responses were compared to those of healthcare workers without co-morbidities. In a subgroup of 40 patients, B- and T-cell responses were also compared to controls. Results: At d31, d90 and d180 after BNT162b2 vaccine, no detectable SARS-CoV-2 IgG response was observed in 5.9%, 3.9% and 7.2% of LC patients as compared to 0 controls (p < 0.03). A delay in B-cell and lack of prompt T-cell response compared to healthcare workers was also registered. A significant correlation between antibody titers and cellular response was observed. A MELD score > 8 was the only independent predictor of poor d31 response (p = 0.028). Conclusions: Our results suggest that cirrhotic patients have a slower and in <10% suboptimal immune response to SARS-CoV-2 vaccination. Rates of breakthrough infections were comparable between cirrhotics and controls. The booster dose was critical in inducing both humoral and cellular responses comparable to controls.

Comparative analysis of human immune responses following SARS-CoV-2 vaccination with BNT162b2, mRNA-1273, or Ad26.COV2.S

SARS-CoV-2 vaccines BNT162b2, mRNA-1273, and Ad26.COV2.S received emergency use authorization by the U.S. Food and Drug Administration in 2020/2021. Individuals being vaccinated were invited to participate in a prospective longitudinal comparative study of immune responses elicited by the three vaccines. In this observational cohort study, immune responses were evaluated using a SARS-CoV-2 spike protein receptor-binding domain ELISA, SARS-CoV-2 virus neutralization assays and an IFN- γ ELISPOT assay at various times over six months following initial vaccination. mRNA-based vaccines elicited higher magnitude humoral responses than Ad26.COV2.S; mRNA-1273 elicited the most durable humoral response, and all humoral responses waned over time. Neutralizing antibodies against the Delta variant were of lower magnitude than the wild-type strain for all three vaccines. mRNA-1273 initially elicited the greatest magnitude of T cell response, but this declined by 6 months. Declining immunity over time supports the use of booster dosing, especially in the setting of emerging variants.

Cellular Immune Response to BNT162b2 mRNA COVID-19 Vaccine in a Large Cohort of Healthcare Workers in a Tertiary Care University Hospital

We describe the results of a T-cell immunity evaluation performed after a median elapsed time of 7 months from second-dose BNT162b2 vaccine administration, in a representative sample of 419 subjects from a large cohort of hospital workers. Overall, the Quantiferon SARS-CoV-2 assay detected a responsive pattern in 49.9%, 59.2% and 68.3% of subjects to three different antigenic stimuli from SARS-CoV-2, respectively, with 72.3% of positivity to at least one antigenic stimulus. Potential predictors of cellular response were explored by multivariable analyses; factors associated with positivity to cellular response (to Ag1 antigenic stimulus) were a previous SARS-CoV-2 infection (OR = 4.24, 95% CI 2.34−7.67, p < 0.001), increasing age (per year: OR = 1.03 95% CI 1.01−1.06, p = 0.019 and currently smoking (compared to never smoking) (OR = 1.93, 95% CI 1.11−3.36, p = 0.010). Increasing time interval between vaccine administration and T-cell test was associated with decreasing cellular response (per week of time: OR = 0.94, 95% CI 0.91−0.98, p = 0.003). A blood group A/AB/B (compared to group O) was associated with higher levels of cellular immunity, especially when measured as Ag2 antigenic stimulus. Levels of cellular immunity tended to be lower among subjects that self-reported an autoimmune disorder or an immunodeficiency and among males. Further studies to assess the protective significance of different serological and cellular responses to the vaccine toward the risk of reinfection and the severity of COVID-19 are needed to better understand these findings.