Risk Factors for Weak Antibody Response of SARS-CoV-2 Vaccine in Adult Solid Organ Transplant Recipients: A Systemic Review and Meta-Analysis

Clinical Features and Prognostic Predictors in Patients with Renal Transplant Complicated by SARS-CoV-2 Infection, a Retrospective Single-Center Study

Background

This study examines the clinical outcomes and prognostic factors of COVID-19 in renal transplant recipients. Given their immunosuppressed status, these patients are at higher risk of severe complications from COVID-19. The study aims to provide healthcare professionals with critical insights for diagnosing and managing this vulnerable population.

Patients and methods

This retrospective cohort study included adult renal transplant recipients diagnosed with COVID-19. Data on demographics, medical history, laboratory results, and patient outcomes were analyzed to identify clinical characteristics and prognostic factors.

Results

This study included 115 renal transplant recipients with COVID-19, predominantly male, with a mortality rate of 10.4% (12 deaths). The overall vaccination rate was 20%. Univariate analysis showed significant differences between survivors and non-survivors in initial serum creatinine levels, and percentages of neutrophils, monocytes, and lymphocytes, along with CRP levels on day 3. Additionally, CRP levels, hemoglobin, and platelet counts on day 7 also differed significantly. Multivariate analysis identified CRP levels on days 3 and 7, day 7 hemoglobin and platelet counts, and concurrent bacterial infections as independent risk factors for mortality.

Conclusion

Elevated CRP levels, renal impairment, and bacterial co-infections play a significant role in the outcomes of COVID-19 in kidney transplant recipients. This study highlights the importance of monitoring these factors for early identification and management of high-risk patients.

Measures to Increase Immunogenicity of SARS-CoV-2 Vaccines in Solid Organ Transplant Recipients: A Narrative Review

Purpose of review: To review the data on the immunogenicity of COVID-19 vaccines, administered by different strategies, in solid organ transplant recipients (SOTRs). Recent findings: COVID-19 booster vaccines were given to SOTRs as a widespread practice in many transplant centers, mostly as the third and/or fourth dose in an extended vaccine series, with a significantly improved humoral response compared with the initial two-dose scheme. However, one-third of SOTRs remained unresponsive, despite these boosters. Next steps: Vaccination with standard dosing remains the most feasible strategy for attaining protection against COVID-19. Additional booster doses and temporarily holding or reducing mycophenolate mofetil/mycophenolic acid may provide immunogenicity to vaccines, according to recent studies demonstrating some efficacy with these measures. Preexposure prophylaxis with monoclonal antibodies showed benefit in immunocompromised patients but is no longer recommended by the National Institutes of Health (NIH) due to diminished efficacy against Omicron and recent variants. Screening for the presence and titers of SARS-CoV-2-specific antibodies in SOTRs is not recommended in most clinical settings. T cell-based techniques are needed to evaluate vaccine efficacy and risk of infection. As SARS-CoV-2 continues to evolve, new vaccines based on conservative protein component/complexes of the COVID virus, in addition to its spike protein, are warranted to offer prolonged protection.

The Influence of COVID-19 in Endocrine Research: Critical Overview, Methodological Implications and a Guideline for Future Designs

The COVID-19 pandemic has changed many aspects of people's lives, including not only individual social behavior, healthcare procedures, and altered physiological and pathophysiological responses. As a result, some medical studies may be influenced by one or more hidden factors brought about by the COVID-19 pandemic. Using the literature review method, we are briefly discussing the studies that are confounded by COVID-19 and facemask-induced partiality and how these factors can be further complicated with other confounding variables. Facemask wearing has been reported to produce partiality in studies of ophthalmology (particularly dry eye and related ocular diseases), sleep studies, cognitive studies (such as emotion-recognition accuracy research, etc.), and gender-influenced studies, to mention a few. There is a possibility that some other COVID-19 related influences remain unrecognized in medical research. To account for heterogeneity, current and future studies need to consider the severity of the initial illness (such as diabetes, other endocrine disorders), and COVID-19 infection, the timing of analysis, or the presence of a control group. Face mask-induced influences may confound the results of diabetes studies in many ways.

Increasing Antibody Responses to Five Doses of SARS-CoV-2 mRNA Vaccine in Lung Transplant Patients

PURPOSE

COVID-19 causes high mortality in Lung Transplant (LTx) patients, therefore vaccination in this population is potentially life-saving. However, the antibody response is impaired after three vaccinations in LTx patients. We questioned whether this response might be increased, and therefore studied the serological IgG antibody response across up to five doses of the SARS-CoV-2 vaccine. In addition, risk factors for non-response were investigated.

METHODS

In this large retrospective cohort study, antibody responses were assessed after 1-5 mRNA-based SARS-CoV-2 vaccines in all LTx patients between February 2021 and September 2022. A positive vaccine response was defined as an IgG level ≥ 300 BAU/mL. Positive antibody responses due to COVID-19 infection were excluded from the analysis. Outcome and clinical parameters were compared between responders and non-responders, and multivariable logistic regression analysis was performed to determine the risk factors for vaccine-response failure.

RESULTS

The antibody responses of 292 LTx patients were analyzed. Positive antibody response to 1-5 SARS-CoV-2 vaccinations occurred in 0%, 15%, 36%, 46%, and 51%, respectively. During the study period, 146/292 (50%) of the vaccinated individuals tested positive for SARS-CoV-2 infection. The COVID-19-related mortality was 2.7% (4/146), and all four patients were non-responders. Risk factors associated with non-response to SARS-CoV-2 vaccines in univariable analyses were age (p = 0.004), chronic kidney disease (CKD) (p = 0.006), and shorter time since transplantation (p = 0.047). In the multivariable analysis, they were CKD (p = 0.043), and shorter time since transplantation (p = 0.028).

CONCLUSION

A two- to five-dose regime of SARS-CoV-2 vaccines in LTx patients increases the probability of vaccine response and results in a cumulative vaccine response in 51% of the LTx population. LTx patient antibody response to SARS-CoV-2 vaccinations is therefore impaired, especially in patients shortly after LTx, patients with CKD, and the elderly.

Comparable cellular and humoral immunity upon homologous and heterologous COVID-19 vaccination regimens in kidney transplant recipients

Background

Kidney transplant recipients (KTRs) are at high risk for a severe course of coronavirus disease 2019 (COVID-19); thus, effective vaccination is critical. However, the achievement of protective immunogenicity is hampered by immunosuppressive therapies. We assessed cellular and humoral immunity and breakthrough infection rates in KTRs vaccinated with homologous and heterologous COVID-19 vaccination regimens.

Method

We performed a comparative in-depth analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–specific T-cell responses using multiplex Fluorospot assays and SARS-CoV-2-specific neutralizing antibodies (NAbs) between three-times homologously (n = 18) and heterologously (n = 8) vaccinated KTRs.

Results

We detected SARS-CoV-2-reactive T cells in 100% of KTRs upon third vaccination, with comparable frequencies, T-cell expression profiles, and relative interferon γ and interleukin 2 production per single cell between homologously and heterologously vaccinated KTRs. SARS-CoV-2-specific NAb positivity rates were significantly higher in heterologously (87.5%) compared to homologously vaccinated (50.0%) KTRs (P < 0.0001), whereas the magnitudes of NAb titers were comparable between both subcohorts after third vaccination. SARS-CoV-2 breakthrough infections occurred in equal numbers in homologously (38.9%) and heterologously (37.5%) vaccinated KTRs with mild-to-moderate courses of COVID-19.

Conclusion

Our data support a more comprehensive assessment of not only humoral but also cellular SARS-CoV-2-specific immunity in KTRs to provide an in-depth understanding about the COVID-19 vaccine–induced immune response in a transplant setting.

Effectiveness of vaccination against SARS-CoV-2 and the need for alternative preventative approaches in immunocompromised individuals: a narrative review of systematic reviews

INTRODUCTION

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including administration of booster doses, continues to be the most effective method for controlling COVID-19-related complications including progression to severe illness and death.However, there is mounting evidence that more needs to be done to protect individuals with compromised immune function.

AREAS COVERED

Here, we review the effectiveness of COVID-19 vaccination in immunocompromised patients, including those with primary immunodeficiencies, HIV, cancer (including hematological malignancies), solid organ transplant recipients and chronic kidney disease, as reported in systematic reviews/meta-analyses published over a 12-month period in PubMed. Given the varied responses to vaccination patients with compromised immune function, a major goal of this analysis was to try to identify specific risk-factors related to vaccine failure.

EXPERT OPINION

COVID-19 remains a global problem, with new variants of concern emerging at regular intervals. There is an ongoing need for optimal vaccine strategies to combat the pandemic. In addition, alternative treatment approaches are needed for immunocompromised patients who may not mount an adequate immune response to current COVID-19 vaccines. Identification of high-risk patients, and the introduction of newer antiviral approaches such as monoclonal antibodies, will offer physicians therapeutic options for such vulnerable individuals.

Antibody acquisition after second and third SARS-CoV-2 vaccinations in Japanese kidney transplant patients: a prospective study

BACKGROUND

Kidney transplant patients have lower antibody acquisition after SARS-CoV-2 vaccination. The efficacy of vaccines in Japanese kidney transplant patients with specific characteristics, such as predominant living-donor, ABO-incompatible kidney transplant, and low-dose immunosuppression, requires verification.

METHODS

We conducted a prospective study to estimate anti-SARS-CoV-2 antibody levels in 105 kidney transplant patients and 57 controls. Blood samples were obtained before vaccination, 1, 3, and 6 months after second vaccination, and 1 month after third vaccination. We investigated antibody acquisition rates, antibody levels, and factors associated with antibody acquisition.

RESULTS

One month after second vaccination, antibody acquisition was 100% in the controls but only 36.7% in the kidney transplant group (P < 0.001). Antibody levels in positive kidney transplant patients were also lower than in the controls (median, 4.9 arbitrary units vs 106.4 arbitrary units, respectively, P < 0.001). Years after kidney transplant (odds ratio 1.107, 95% confidence interval 1.012-1.211), ABO-incompatible kidney transplant (odds ratio 0.316, 95% confidence interval 0.101-0.991) and mycophenolate mofetil use (odds ratio 0.177, 95% confidence interval 0.054-0.570) were significant predictors for antibody acquisition after second vaccination. After third vaccination, antibody positivity in the kidney transplant group increased to 75.3%, and antibody levels in positive patients were 71.7 arbitrary units. No factors were associated with de novo antibody acquisition.

CONCLUSIONS

In Japanese kidney transplant patients, years after kidney transplant, ABO-incompatible kidney transplant and mycophenolate mofetil use were predictors for antibody acquisition after second vaccination. Third vaccination improves antibody status even in patients who were seronegative after the second vaccination.

Humoral and T-cell response 12 months after the first BNT162b2 vaccination in solid organ transplant recipients and controls: Kinetics, associated factors, and role of SARS-CoV-2 infection

Introduction

We investigated humoral and T-cell responses within 12 months after first BNT162b2 vaccine in solid organ transplant (SOT) recipients and controls who had received at least three vaccine doses. Furthermore, we compared the immune response in participants with and without previous SARS-CoV-2 infection.

Methods

We included adult liver, lung, and kidney transplant recipients, and controls were selected from a parallel cohort of healthcare workers.

Results

At 12th-month, the IgG geometric mean concentrations (GMCs) (P<0.001), IgA GMCs (P=0.003), and median IFN-γ (P<0.001) were lower in SOT recipients than in controls. However, in SOT recipients and controls with previous infection, the neutralizing index was 99%, and the IgG, and IgA responses were comparable. After adjustment, female-sex (aOR: 3.6, P<0.009), kidney (aOR: 7.0, P= 0.008) or lung transplantation (aOR: 7.5, P= 0.014), and use of mycophenolate (aOR: 5.2, P=0.03) were associated with low IgG non response. Age (OR:1.4, P=0.038), time from transplantation to first vaccine (OR: 0.45, P<0.035), and previous SARS-CoV-2 infection (OR: 0.14, P<0.001), were associated with low IgA non response. Diabetes (OR:2.4, P=0.044) was associated with T-cell non response.

Conclusion

In conclusion, humoral and T-cell responses were inferior in SOT recipients without previous SARS-CoV-2 infection but comparable to controls in SOT recipients with previous infection.

Immunogenicity profiling and distinct immune response in liver transplant recipients vaccinated with SARS-CoV-2 inactivated vaccines

SARS-CoV-2 vaccination has been recommended for liver transplant (LT) recipients. However, our understanding of inactivated vaccine stimulation of the immune system in regulating humoral and cellular immunity among LT recipients is inadequate. Forty-six LT recipients who received two-dose inactivated vaccines according to the national vaccination schedule were enrolled. The clinical characteristics, antibody responses, single-cell peripheral immune profiling, and plasma cytokine/chemokine/growth factor levels were recorded. Sixteen (34.78%) LT recipients with positive neutralizing antibody (nAb) were present in the Type 1 group. Fourteen and 16 LT recipients with undetected nAb were present in the Type 2 and Type 3 groups, respectively. Time from transplant and lymphocyte count were different among the three groups. The levels of anti-RBD and anti-S1S2 decreased with decreasing neutralizing inhibition rates. Compared to the Type 2 and Type 3 groups, the Type 1 group had an enhanced innate immune response. The proportions of B, DNT, and CD3+CD19+ cells were increased in the Type 1 group, whereas monocytes and CD4+ T cells were decreased. High CD19, high CD8+CD45RA+ cells, and low effector memory CD4+/naïve CD4+ cells of the T-cell populations were present in the Type 1 group. The Type 1 group had higher concentrations of plasma CXCL10, MIP-1 beta, and TNF-alpha. No severe adverse events were reported in all LT recipients. We identified the immune responses induced by inactivated vaccines among LT recipients and provided insights into the identification of immunotypes associated with the responders.

T Cell and Antibody Response Following Double Dose of BNT162b2 mRNA Vaccine in SARS-CoV-2 Naïve Heart Transplant Recipients

Introduction: Preliminary studies have suggested a low post-vaccination antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in heart transplant(HTx)recipients. Although many studies have focused on the role of antibodies in vaccine-induced protection against SARS-CoV-2, the role of T cell immunity is less well characterized. To date, data regarding seroconversion and T cell response after mRNA SARS-CoV-2 vaccination in patients undergoing HTx are scarce. Therefore, the present study aimed to assess the specific memory humoral and cellular responses after two doses of the BNT162b2 vaccine in HTx recipients. Methods: Blood was drawn from heart transplant (HTx) recipients at two pre-specified time points after the first and second vaccine doses to measure both the anti-SARS-CoV-2 antibody response against the spike protein and the SARS-CoV-2-reactive T cell response. Results: Our study included 34 SARS-CoV-2 naïve HTx recipients (mean age, 61 ± 11 years). The mean time from transplantation to the first vaccine dose is 10 ± 10 years. Subgroup analysis (n = 21) demonstrated that after the first vaccine dose, only 14% had antibodies and 19% had a SARS-CoV-2-reactive T-cell response, which increased to 41% and 53%, respectively, after the second dose. Interestingly, 20% of patients with no antibodies after the second dose still had a positive SARS-CoV-2-reactive T cell response. The percentage of patients with positive S-IgG antibody titers was significantly higher 5 years after transplantation (18% 0–5 years post-TX vs. 65% 5 years post-TX, p = 0.013). Similarly, 5 years after heart transplantation, the percentage of patients with a T cell response was significantly higher (35% 0–5 years post-TX vs. 71% 5 years post-TX, p = 0.030). Conclusions: In SARS-CoV-2 naïve HTx recipients, post-vaccination antibody titers but also SARS-CoV-2 specific T cell response are low. Therefore, the protection from SARS-CoV-2 that is generally attributed to vaccination should be regarded with caution in HTx recipients.