Humoral vaccine response and breakthrough infections in kidney transplant recipients during the COVID-19 pandemic: a nationwide cohort study

Comparison of immune responses to SARS-CoV-2 spike following Omicron infection or Omicron BA.4/5 vaccination in kidney transplant recipients

Background

The emergence of novel SARS-CoV-2 variants challenges immunity, particularly among immunocompromised kidney transplant recipients (KTRs). To address this, vaccines have been adjusted to circulating variants. Despite intensive vaccination efforts, SARS-CoV-2 infections surged among KTRs during the Omicron wave, enabling a direct comparison of variant-specific immunity following-vaccination against Omicron BA.4/5 or Omicron infection in KTRs.

Methods

98 SARS-CoV-2 naïve KTRs who had received four vaccine doses were studied. Before and after a 5th antigen exposure, either via the bivalent vaccine composed of ancestral SARS-CoV-2 and Omicron BA.4/5 (29 KTRs) or via natural infection with Omicron (38 BA.4/5, 31 BA.1/2), spike-specific T cells were quantified using Elispot and serum pseudovirus neutralizing activity was assessed against the ancestral Wuhan strain, BA.5 and XBB.1.5.

Results

Compared to BA.4/5 vaccination, spike-specific T-cell responses and neutralization activity were higher up to six months post-Omicron infection and reached levels similar to healthy controls. Vaccinated KTRs showed modestly boosted neutralization activity against the Wuhan strain and BA.5, but not XBB.1.5. Baseline immunity correlated with immune responses three months post-vaccination and post-infection, indicating a predictive value for peak immune responses. Tixagevimab/Cilgavimab treatment was associated with robust neutralization of the Wuhan strain, but ineffective against XBB.1.5.

Conclusion

The BA.4/5 vaccine improved neutralizing activity against the BA.4/5 variant, but not against the subsequently circulating XBB.1.5 variant in KTRs. Conversely, omicron infection boosted T cells and humoral responses more effectively, showing efficacy against XBB.1.5. These findings suggest that infection-induced immunity associates with greater protection than vaccination against future variants in KTRs.

Risk factors for SARS-CoV-2 pneumonia among renal transplant recipients in Omicron pandemic-a prospective cohort study

BACKGROUND

The coronavirus disease (COVID-19) pandemic is a global health emergency, and SARS-CoV-2 pneumonia poses significant challenges to health systems worldwide. Renal transplant recipients (RTRs) are a special group and are more vulnerable to viral pneumonia. However, few studies have elucidated the risk factors of SARS-CoV-2 pneumonia in RTRs infected with COVID-19. This study aimed to build a risk prediction model for SARS-CoV-2 pneumonia among RTRs based on demographic and clinical information.

METHODS

We conducted a prospective cohort study among 383 RTRs (age ≥ 18 years) diagnosed with COVID-19 from December 21, 2022, to March 26, 2023. Patients' demographic and clinical information was collected through a questionnaire survey combined with electronic medical records. A stepwise logistic regression model was established to test the predictors of SARS-CoV-2 pneumonia. We assessed the diagnostic performance of the model by calculating the area under the curve (AUC) of the receiver operating characteristic (ROC) and calibration using the Hosmer-Lemeshow (HL) goodness-of-fit test.

RESULTS

Our study showed that the incidence of SARS-CoV-2 pneumonia among RTRs was 31.1%. Older age (OR = 2.08-3.37,95%CI:1.05-7.23), shorter post-transplantation duration (OR = 0.92,95% CI: 0.87,0.99), higher post-transplant Charlson Comorbidity Index (CCI) (OR = 1.84, 95%CI: 1.14,2.98), pulmonary infection history (OR = 3.44, 95%CI: 1.459, 8.099, P = 0.005), fatigue (OR = 2.11, 95%CI: 1.14, 3.90), cough (OR = 2.03, 95%CI: 1.08, 3.81), and lower estimated glomerular filtration rate (eGFR) at COVID-19 diagnosis (OR = 0.98, 95%CI:0.97,0.99) predicted a higher risk for SARS-CoV-2 pneumonia. The model showed good diagnostic performance with Chi-Square = 10.832 (P > 0.05) and AUC = 0.839 (P < 0.001).

CONCLUSIONS

Our study showed a high incidence of SARS-CoV-2 pneumonia among RTRs, and we built a risk prediction model for SARS-CoV-2 pneumonia based on patients' demographic and clinical characteristics. The model can help identify RTRs infected with COVID-19 at high risk of SARS-CoV-2 pneumonia to inform timely, targeted, and effective prevention and intervention efforts.

COVID-19 Vaccination Recommendations for Immunocompromised Patient Populations: Delphi Panel and Consensus Statement Generation in the United States

INTRODUCTION

The United States Advisory Committee on Immunization Practices (ACIP) and the Centers for Disease Control (CDC) recommend COVID-19 vaccines for all immunocompromised individuals. Certain disease groups are at increased risk of comorbidity and death for which disease-specific recommendations should be considered. The objective of the Delphi panel of experts was to summarize expert consensus on COVID-19 vaccinations for patients with rheumatologic disease, renal disease, hematologic malignancy and solid organ transplant (SOT) in the US.

METHODS

A two-stage Delphi panel method was employed, starting with qualitative interviews with key opinion leaders (KOLs) in the four disease areas (n = 4 KOLs, n = 16 total) followed by three rounds of iterative revision of disease-specific COVID-19 vaccine recommendations. Final consensus was rated after the third round. Statements addressed primary and booster dosing (e.g., number and frequency) and other considerations such as vaccine type or heterologous messenger ribonucleic acid (mRNA) vaccination. Following the Delphi Panel, an online survey was conducted to assess physician agreement within the disease areas (n = 50 each, n = 200 total) with the consensus statements.

RESULTS

Moderate to strong consensus was achieved for all primary series vaccination statements across disease groups, except one in hematology. Similarly, moderate to strong consensus was achieved for all booster series statements in all disease areas. However, statements on antibody titer measurements for re-vaccination considerations and higher dosages for immunocompromised patients did not reach agreement. Overall, approximately 62%-96% of physicians strongly agreed with the primary and booster vaccine recommendations. However, low agreement (29%-69%) was found among physicians for time interval between disease-specific treatment and vaccination, recommendations for mRNA vaccines, heterologous mRNA vaccination, antibody titer measurement and higher vaccine dosage for immunocompromised groups.

CONCLUSION

Consensus was achieved for disease-specific COVID-19 vaccine recommendations concerning primary and booster series vaccines and was generally well accepted by practicing physicians.

Delphi Panel Consensus Statement Generation: COVID-19 Vaccination Recommendations for Immunocompromised Populations in the European Union

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic has caused unprecedented pressure on healthcare systems globally. The lack of quality guidelines on the management of COVID-19 in rheumatologic disease, renal disease, hematological malignancy, and solid organ transplant recipients has resulted in a wide variation in clinical practice.

METHODS

Using a Delphi process, a panel of 16 key opinion leaders developed clinical practice statements regarding vaccine recommendations in areas where standards are absent or limited. Agreement among practicing physicians with consensus statements was also assessed via an online physician survey. The strength of the consensus was determined by the following rating system: a strong rating was defined as all four key opinion leaders (KOLs) rating the statement ≥ 8, a moderate rating was defined as three out of four KOLs rating the statement ≥ 8, and no consensus was defined as less than three out of four KOLs provided a rating of ≤ 8. Specialists voted on agreement with each consensus statement for their disease area using the same ten-point scoring system.

RESULTS

Key opinion leaders in rheumatology, nephrology, and hematology achieved consensuses for all nine statements pertaining to the primary and booster series with transplant physicians reaching consensus on eight of nine statements. Experts agreed that COVID-19 vaccines are safe, effective, and well tolerated by patients with rheumatological conditions, renal disease, hematologic malignancy, and recipients of solid organ transplants. The Delphi process yielded strong to moderate suggestions for the use of COVID-19 messenger ribonucleic acid (mRNA) vaccines and the necessity of the COVID-19 booster for the immunocompromised population. The expert panel had mixed feelings concerning the measurement of antibody titers, higher-dose mRNA vaccines, and the development of disease-specific COVID-19 guidance.

CONCLUSIONS

These results confirmed the necessity of COVID-19 vaccines and boosters in immunocompromised patients with rheumatologic disease, renal disease, hematological malignancy, and solid organ transplant recipients. Statements where consensus was not achieved were due to absent or limited evidence.

Incidence and Severity of COVID-19 in Relation to Anti-Receptor-Binding Domain IgG Antibody Level after COVID-19 Vaccination in Kidney Transplant Recipients

Kidney transplant recipients (KTRs) elicit an impaired immune response after COVID-19 vaccination; however, the exact clinical impact remains unclear. We therefore analyse the relationship between antibody levels after vaccination and the risk of COVID-19 in a large cohort of KTRs. All KTRs living in the Netherlands were invited to send a blood sample 28 days after their second COVID-19 vaccination for measurement of their IgG antibodies against the receptor-binding domain of the SARS-CoV-2 spike protein (anti-RBD IgG). Information on COVID-19 was collected from the moment the blood sample was obtained until 6 months thereafter. Multivariable Cox and logistic regression analyses were performed to analyse which factors affected the occurrence and severity (i.e., hospitalization and/or death) of COVID-19. In total, 12,159 KTRs were approached, of whom 2885 were included in the analyses. Among those, 1578 (54.7%) became seropositive (i.e., anti-RBD IgG level >50 BAU/mL). Seropositivity was associated with a lower risk for COVID-19, also after adjusting for multiple confounders, including socio-economic status and adherence to COVID-19 restrictions (HR 0.37 (0.19-0.47), p = 0.005). When studied on a continuous scale, we observed a log-linear relationship between antibody level and the risk for COVID-19 (HR 0.52 (0.31-0.89), p = 0.02). Similar results were found for COVID-19 severity. In conclusion, antibody level after COVID-19 vaccination is associated in a log-linear manner with the occurrence and severity of COVID-19 in KTRs. This implies that if future vaccinations are indicated, the aim should be to reach for as high an antibody level as possible and not only seropositivity to protect this vulnerable patient group from disease.

Hybrid and SARS-CoV-2-vaccine immunity in kidney transplant recipients

BACKGROUND

Kidney transplant recipients (KTR) are at high risk for severe COVID-19 and have demonstrated poor response to vaccination, making it unclear whether successive vaccinations offer immunity and protection.

METHODS

We conducted a serologically guided interventional study where KTR patients that failed to seroconvert were revaccinated and also monitored seroconversion of KTR following the Norwegian vaccination program. We analysed IgG anti-RBD Spike responses from dose 2 (n = 432) up to after the 6th (n = 37) mRNA vaccine dose. The frequency and phenotype of Spike-specific T and B cell responses were assessed in the interventional cohort after 3-4 vaccine doses (n = 30). Additionally, we evaluated the Specific T and B cell response to breakthrough infection (n = 32), measured inflammatory cytokines and broadly cross-neutralizing antibodies, and defined the incidence of COVID-19-related hospitalizations and deaths. The Norwegian KTR cohort has a male dominance (2323 males, 1297 females), PBMC were collected from 114 male and 78 female donors.

FINDINGS

After vaccine dose 3, most KTR developed Spike-specific T cell responses but had significantly reduced Spike-binding B cells and few memory cells. The B cell response included a cross-reactive subset that could bind Omicron VOC, which expanded after breakthrough infection (BTI) and gave rise to a memory IgG+ B cell response. After BTI, KTR had increased Spike-specific T cells, emergent non-Spike T and B cell responses, and a systemic inflammatory signature. Late seroconversion occurred after doses 5-6, but 38% (14/37) of KTR had no detectable immunity even after multiple vaccine doses.

INTERPRETATION

Boosting vaccination can induce Spike-specific immunity that may expand in breakthrough infections highlighting the benefit of vaccination to protect this vulnerable population.

FUNDING

CEPI and internal funds.