Protective Effect of Vaccine Doses and Antibody Titers Against SARS-CoV-2 Infection in Kidney Transplant Recipients

Comparative Effectiveness of mRNA-1273 and BNT162b2 COVID-19 Vaccines Among Adults with Underlying Medical Conditions: Systematic Literature Review and Pairwise Meta-Analysis Using GRADE

INTRODUCTION

This systematic literature review and pairwise meta-analysis evaluated the comparative effectiveness of mRNA-1273 versus BNT162b2 in patients with at least one underlying medical condition at high risk for severe COVID-19.

METHODS

MEDLINE, Embase, and Cochrane databases were searched for relevant articles from January 1, 2019 to February 9, 2024. Studies reporting effectiveness data from at least two doses of mRNA-1273 and BNT162b2 vaccination in adults with medical conditions at high risk of developing severe COVID-19 according to the US Centers for Disease Control and Prevention were included. Outcomes of interest were SARS-CoV-2 infection (overall, symptomatic, and severe), hospitalization due to COVID-19, and death due to COVID-19. Risk ratios (RRs) were calculated with random effects models. Subgroup analyses by specific medical conditions, number of vaccinations, age, and SARS-CoV-2 variant were conducted. Heterogeneity between studies was estimated with chi-square testing. The certainty of evidence was assessed using the Grading of Recommendations, Assessments, Development, and Evaluations framework.

RESULTS

Sixty-five observational studies capturing the original/ancestral-containing primary series to Omicron-containing bivalent original-BA4-5 vaccinations were included in the meta-analysis. mRNA-1273 was associated with significantly lower risk of SARS-CoV-2 infection (RR, 0.85 [95% CI, 0.79-0.92]; I2 = 92.5%), symptomatic SARS-CoV-2 infection (RR, 0.75 [95% CI, 0.65-0.86]; I2 = 62.3%), severe SARS-CoV-2 infection (RR, 0.83 [95% CI, 0.78-0.89]; I2 = 38.0%), hospitalization due to COVID-19 (RR, 0.88 [95% CI, 0.82-0.94]; I2 = 38.7%), and death due to COVID-19 (RR, 0.84 [95% CI, 0.76-0.93]; I2 = 1.3%) than BNT162b2. Findings were generally consistent across subgroups. Evidence certainty was low or very low because sufficiently powered randomized controlled trials are impractical in this heterogeneous population.

CONCLUSION

Meta-analysis of 65 observational studies showed that vaccination with mRNA-1273 was associated with a significantly lower risk of SARS-CoV-2 infection and COVID-19-related hospitalization and death than BNT162b2 in patients with medical conditions at high risk of severe COVID-19.

SARS-CoV-2 Infection Is Associated with an Accelerated eGFR Decline in Kidney Transplant Recipients up to Four Years Post Infection

Background/Objectives: Although kidney transplant recipients (KTRs) who are immune-compromised have been shown to be at high risk of adverse acute COVID-19 outcomes (i.e., mortality and critical illness), the long-term outcomes of KTRs with a history of SARS-CoV-2 infection are unknown. We aimed to compare long-term outcomes of KTRs with and without exposure to SARS-CoV-2. Methods: This study retrospectively evaluated 1815 KTRs in the Montefiore Health System from 4 January 2001 to 31 January 2024. The final cohorts consisted of KTRs who survived COVID-19 (n = 510) and matched KTRs without COVID-19 (n = 510, controls). Outcomes were defined as all-cause mortality and changes in estimated glomerular filtration rate (eGFR) and urine protein to creatinine ratio (UPCR) from 30 days up to four years post index date. Kaplan-Meier survival analysis and Cox proportional modeling were performed for mortality. Generalized estimating equations were used to analyze changes in eGFR and UPCR across time. Results: There was no significant group difference in long-term all-cause mortality (adjusted hazard ratio = 0.66, [0.43, 1.01] p = 0.057). eGFR in controls and COVID-19 patients before infection similarly decreased -0.98 units/year [-1.50, -0.46]. By contrast, eGFR declined at a significantly greater rate (-1.80 units/year [-2.45, -1.15]) in KTRs after COVID-19 compared to KTRs without COVID-19. This association was only seen among male and not female KTRs. COVID-19 status was not significantly associated with rate of change in UPCR or acute kidney rejection rate. Conclusions: SARS-CoV-2 infection was associated with an accelerated decline in eGFR up to four years post infection, suggesting potential long-term implications for graft health. These findings underscore the importance of vigilant monitoring and management of kidney function post SARS-CoV-2 infection in this vulnerable population.

Efficacy and safety of COVID-19 vaccination in solid organ transplant recipients: A systematic review and network meta-analysis

The impact of COVID-19 vaccination on clinical outcomes in solid organ transplant (SOT) recipients remains unclear. This systematic review and network meta-analysis sought to assess the efficacy and safety of COVID-19 vaccination in SOT recipients. We searched 6 databases from inception to March 1, 2024 for randomized controlled trials (RCTs) and observational studies evaluating different COVID-19 vaccination strategies in SOT recipients. Based on patient-important outcomes, we performed frequentist random-effects pairwise meta-analyses and network meta-analyses, separating RCTs and nonrandomized evidence, and used the Grading of Recommendation, Assessment, Development, and Evaluation approach to assess our certainty in the evidence. We included 6 RCTs (N = 814) and 43 observational studies (N = 125 199). Overall, there is a paucity of randomized evidence evaluating COVID-19 vaccines in SOT recipients. The nonrandomized evidence evaluating COVID-19 vaccination strategies patient-important outcomes, including COVID-19 infection, mortality, hospitalization, ICU admission, and rejection, demonstrated low to very low certainty due to the included studies' risk of bias. Throughout the COVID-19 pandemic, clinicians and SOT recipients worked with minimal, very low-quality evidence in relation to COVID-19 vaccines in this population. In the instance of future public health emergencies, clinicians and researchers should collaborate closely with patient partners to ensure there is sufficient evidence in the transplant population on patient-important outcomes.

Antibody and T-Cell Response to Bivalent Booster SARS-CoV-2 Vaccines in People With Compromised Immune Function: COVERALL-3 Study

BACKGROUND

Bivalent messenger RNA (mRNA) vaccines, designed to combat emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, incorporate ancestral strains and a new variant. Our study assessed the immune response in previously vaccinated individuals of the Swiss HIV Cohort Study (SHCS) and the Swiss Transplant Cohort Study (STCS) following bivalent mRNA vaccination.

METHODS

Eligible SHCS and STCS participants received approved bivalent mRNA SARS-CoV-2 vaccines (mRNA-1273.214 or BA.1-adapted BNT162b2) within clinical routine. Blood samples were collected at baseline, 4 weeks, 8 weeks, and 6 months postvaccination. We analyzed the proportion of participants with anti-spike protein antibody response ≥1642 units/mL (indicating protection against SARS-CoV-2 infection), and in a subsample T-cell response (including mean concentrations), stratifying results by cohorts and population characteristics.

RESULTS

In SHCS participants, baseline anti-spike antibody concentrations ≥1642 units/mL were observed in 87% (96/112), reaching nearly 100% at follow-ups. Among STCS participants, 58% (35/60) had baseline antibodies ≥1642 units/mL, increasing to 80% at 6 months. Except for lung transplant recipients, all participants showed a 5-fold increase in geometric mean antibody concentrations at 4 weeks and a reduction by half at 6 months. At baseline, T-cell responses were positive in 96% (26/27) of SHCS participants and 36% (16/45) of STCS participants (moderate increase to 53% at 6 months). Few participants reported SARS-CoV-2 infections, side-effects, or serious adverse events.

CONCLUSIONS

Bivalent mRNA vaccination elicited a robust humoral response in individuals with human immunodeficiency virus (HIV) or solid organ transplants, with delayed responses in lung transplant recipients. Despite a waning effect, antibody levels remained high at 6 months and adverse events were rare. Clinical Trials Registration . NCT04805125.

Effectiveness of a Fourth COVID-19 mRNA Vaccine Dose Against the Omicron Variant in Solid Organ Transplant Recipients

BACKGROUND

The effectiveness of booster doses of COVID-19 vaccines in solid organ transplant recipients is unclear. We conducted a population-based matched cohort study using linked administrative healthcare databases from Ontario, Canada to estimate the marginal vaccine effectiveness of a fourth versus third dose of the BNT162b2 and mRNA-1273 vaccines against clinically important outcomes (ie, hospitalization or death) and infection during the era of the Omicron variant.

METHODS

We matched 3120 solid organ transplant recipients with a third COVID-19 vaccine dose (reference) to 3120 recipients with a fourth dose. Recipients were matched on the third dose date (±7 d). We used a multivariable Cox proportional hazards model to estimate the marginal vaccine effectiveness with outcomes occurring between December 21, 2021 and April 30, 2022.

RESULTS

The cumulative incidence of COVID-19-related hospitalization or death was 2.8% (95% confidence interval [CI], 2.0-3.7) in the third dose group compared with 1.1% (95% CI, 0.59-1.8) in the fourth dose group after 84 d of follow-up (P < 0.001). The adjusted marginal vaccine effectiveness was 70% (95% CI, 47-83) against clinically important outcomes and 39% (95% CI, 21-52) against SARS-CoV-2 infection.

CONCLUSIONS

Compared with a third dose, a fourth dose of the COVID-19 vaccine was associated with improved protection against hospitalization, death, and SARS-CoV-2 infection during the Omicron era. Results highlight the importance of a booster COVID-19 vaccine dose in solid organ transplant recipients.

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.