SARS-CoV-2 Spike-specific IFN-γ T-cell Response After COVID-19 Vaccination in Patients With Chronic Kidney Disease, on Dialysis, or Living With a Kidney Transplant

Heterologous and homologous COVID-19 mRNA vaccination schemes for induction of basic immunity show similar immunogenicity regarding long-term spike-specific cellular immunity in healthcare workers

Healthcare workers (HCWs) are recommended to receive at least three spike-antigen exposures to generate basic immunity and to mediate herd protection of vulnerable patients. So far, less attention has been put on the cellular immune response induced by homologous (three BTN162b2mRNA doses) or heterologous (mRNA-1273 as third dose building on two BTN162bmRNA doses) and the immunological impact of breakthrough infections (BTIs). Therefore, in 356 vaccinated HCWs with or without BTIs the Anti-SARS-CoV-2-Spike-IgG concentrations and avidities and B- and T-cell-reactivity against SARS-CoV-2-Spike-S1- and Nucleocapsid-antigens were assessed with Interferon-gamma-ELISpot and by flow-cytometry. HCWs who had hybrid immunity due to BTIs exhibited strong T-cell-reactivity against the Spike-S1-antigen. A lasso regression model revealed a significant reduction in T-cell immune responses among smokers (p < 0.0001), with less significant impact observed for age, sex, heterologous vaccination, body-mass-index, Anti-Nucleocapsid T-cell reactivity, days since last COVID-19-immunization, and Anti-SARS-CoV-2-Spike-IgG. Although subgroup analysis revealed higher Anti-SARS-CoV-2-Spike-IgG after heterologous vaccination, similar cellular reactivity and percentages of Spike-reactive T- and B-cells were found between homologous and heterologous vaccination. Anti-SARS-CoV-2-Spike-IgG concentrations and avidity significantly correlated with activated T-cells. CD4 + and CD8 + responses correlated with each other. A strong long-term cellular immune response should be considered as baseline for recommendations of booster doses in HCWs with prioritization of smokers. HCWs presented significant T-cellular reactivity towards Spike-S1-antigen with particularly strong responses in hybrid immunized HCWs who had BTIs. HCWs without BTI presented similar percentages of Spike-specific B- and T-cells between homologous or heterologous vaccination indicating similar immunogenicity for both mRNA vaccines, BNT162b2mRNA and mRNA-1273.

Repeated COVID-19 Vaccination Drives Memory T- and B-cell Responses in Kidney Transplant Recipients: Results From a Multicenter Randomized Controlled Trial

BACKGROUND

Insight into cellular immune responses to COVID-19 vaccinations is crucial for optimizing booster programs in kidney transplant recipients (KTRs).

METHODS

In an immunologic substudy of a multicenter randomized controlled trial (NCT05030974) investigating different repeated vaccination strategies in KTR who showed poor serological responses after 2 or 3 doses of an messenger RNA (mRNA)-based vaccine, we compared SARS-CoV-2-specific interleukin-21 memory T-cell and B-cell responses by enzyme-linked immunosorbent spot (ELISpot) assays and serum IgG antibody levels. Patients were randomized to receive: a single dose of mRNA-1273 (100 μg, n = 25), a double dose of mRNA-1273 (2 × 100 μg, n = 25), or a single dose of adenovirus type 26 encoding the SARS-CoV-2 spike glycoprotein (Ad26.COV2.S) (n = 25). In parallel, we also examined responses in 50 KTR receiving 100 μg mRNA-1273, randomized to continue (n = 25) or discontinue (n = 25) mycophenolate mofetil/mycophenolic acid. As a reference, the data were compared with KTR who received 2 primary mRNA-1273 vaccinations.

RESULTS

Repeated vaccination increased the seroconversion rate from 21% to 66% in all patients, which was strongly associated with enhanced levels of SARS-CoV-2-specific interleukin-21 memory T cells (odd ratio, 3.84 [1.89-7.78]; P < 0.001) and B cells (odd ratio, 35.93 [6.94-186.04]; P < 0.001). There were no significant differences observed in these responses among various vaccination strategies. In contrast to KTR vaccinated with 2 primary vaccinations, the number of antigen-specific memory B cells demonstrated potential for classifying seroconversion after repeated vaccination (area under the curve, 0.64; 95% confidence interval, 0.37-0.90; P = 0.26 and area under the curve, 0.95; confidence interval, 0.87-0.97; P < 0.0001, respectively).

CONCLUSIONS

Our study emphasizes the importance of virus-specific memory T- and B-cell responses for comprehensive understanding of COVID-19 vaccine efficacy among KTR.

Potent induction of humoral and cellular immunity after bivalent BA.4/5 mRNA vaccination in dialysis patients

Knowledge on immunogenicity of the bivalent Omicron BA.4/5 vaccine in dialysis patients and the effect of a previous infection is limited. Therefore, vaccine-induced humoral and cellular immunity was analyzed in dialysis patients and immunocompetent controls with and without prior infection. In an observational study, 33 dialysis patients and 58 controls matched for age, sex and prior infection status were recruited. Specific IgG, neutralizing antibody activity and cellular immunity towards the spike-antigen from parental SARS-CoV-2 and Omicron-subvariants BA.1, BA.2 and BA.4/5 were analyzed before and 13-18 days after vaccination. The bivalent vaccine led to a significant induction of IgG, neutralizing titers, and specific CD4+ and CD8+ T-cell levels. Neutralizing activity towards the parental strain was higher than towards the Omicron-subvariants, whereas specific T-cell levels towards parental spike and Omicron-subvariants did not differ indicating substantial cross-reactivity. Dialysis patients with prior infection had significantly higher spike-specific CD4+ T-cell levels with lower CTLA-4 expression compared to infection-naive patients. When compared to controls, no differences were observed between infection-naive individuals. Among convalescent individuals, CD4+ T-cell levels were higher in patients and neutralizing antibodies were higher in controls. Vaccination was overall well tolerated in both dialysis patients and controls with significantly less adverse events among patients. In conclusion, our study did not provide any evidence for impaired immunogenicity of the bivalent Omicron BA.4/5 vaccine in dialysis patients. Unlike in controls, previous infection of patients was even associated with higher levels of spike-specific CD4+ T cells, which may reflect prolonged encounter with antigen during infection.

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.

Humoral and cellular immune responses after COVID-19 vaccination of lung transplant recipients and patients on the waiting list: a 6-month follow-up

Background

Data on cellular response and the decay of antibodies and T cells in time are scarce in lung transplant recipients (LTRs). Additionally, the development and durability of humoral and cellular immune responses have not been investigated in patients on the waitlist for lung transplantation (WLs). Here, we report our 6-month follow-up of humoral and cellular immune responses of LTRs and WLs, compared with controls.

Methods

Humoral responses to two doses of the mRNA-1273 vaccination were assessed by determining spike (S)-specific IgG antibodies and neutralizing antibodies. Cellular responses were investigated by interferon gamma (IFN-γ) release assay (IGRA) and IFN-γ ELISpot assay at 28 days and 6 months after the second vaccination.

Results

In LTRs, the level of antibodies and T-cell responses was significantly lower at 28 days after the second vaccination. Also, WLs had lower antibody titers and lower T-cell responses compared with controls. Six months after the second vaccination, all groups showed a decrease in antibody titers and T-cell responses. In WLs, the rate of decline of neutralizing antibodies and T-cell responses was significantly higher than in controls.

Conclusion

Our results show that humoral and cellular responses in LTRs, if they develop, decrease at rates comparable with controls. In contrast, the inferior cellular responses and the rapid decay of both humoral and cellular responses in the WL groups imply that WLs may not be protected adequately by two vaccinations and repeat boostering may be necessary to induce protection that lasts beyond the months immediately post-transplantation.

Vaccination Recommendations in Solid Organ Transplant Adult Candidates and Recipients

Prevention of infections is crucial in solid organ transplant (SOT) candidates and recipients. These patients are exposed to an increased infectious risk due to previous organ insufficiency and to pharmacologic immunosuppression. Besides infectious-related morbidity and mortality, this vulnerable group of patients is also exposed to the risk of acute decompensation and organ rejection or failure in the pre- and post-transplant period, respectively, since antimicrobial treatments are less effective than in the immunocompetent patients. Vaccination represents a major preventive measure against specific infectious risks in this population but as responses to vaccines are reduced, especially in the early post-transplant period or after treatment for rejection, an optimal vaccination status should be obtained prior to transplantation whenever possible. This review reports the currently available data on the indications and protocols of vaccination in SOT adult candidates and recipients.

Cellular immune response of SARS-CoV-2 vaccination in kidney transplant recipients: a systematic review and meta-analysis

Background

Evidence has demonstrated inferior humoral immune responses after SARS-CoV-2 vaccination in kidney transplant recipients compared to the general population. However, data on cellular immune responses in this population have not been established.

Methods

We searched the MEDLINE, Scopus, and Cochrane databases and included studies reporting cellular immune response rates in kidney transplant recipients after receiving SARS-CoV-2 vaccines. Studies that reported factors associated with cellular immune responders or non-responders were also included (PROSPERO: CRD42022375544).

Results

From a total of 1,494 articles searched, 53 articles were included in the meta-analysis. In all, 21 studies assessed cellular immune response by interferon-γ enzyme-linked immunosorbent spot (IFN-γ ELISPOT), 22 studies used interferon-γ release assay (IGRA), and 10 studies used flow cytometric analysis. The pooled response rate after two doses (standard regimen) and three doses of vaccination was 47.5% (95%CI 38.4-56.7%) and 69.1% (95%CI 56.3-80.6%) from IFN-γ ELISPOT, 25.8% (95%CI 19.7-32.4%) and 14.7% (95%CI 8.5-22.2%) from IGRA, and 73.7% (95%CI 55.2-88.8%) and 86.5% (95%CI 75.3-94.9%) from flow cytometry, respectively. Recipients with seroconversion were associated with a higher chance of having cellular immune response (OR 2.58; 95%CI 1.89-3.54). Cellular immune response in kidney transplant recipients was lower than in dialysis patients (OR 0.24; 95%CI 0.16-0.34) and the general population (OR 0.10; 95%CI 0.07-0.14). Age and immunosuppressants containing tacrolimus or corticosteroid were associated with inferior cellular immune response.

Conclusion

Cellular immune response after SARS-CoV-2 vaccination in kidney transplant recipients was lower than in dialysis patients and the general population. Age, tacrolimus, and corticosteroid were associated with poor response. Cellular immune response should also be prioritized in vaccination studies.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022375544.

What has vaccination against COVID-19 in CKD patients taught us?

Effective vaccination strategies are of crucial importance to protecting patients who are vulnerable to infections, such as patients with chronic kidney disease. This is because the decreased efficiency of the immune system in chronic kidney disease impairs vaccine-induced immunisation. COVID-19 has prompted investigation of the immune response to SARS-CoV-2 vaccines in chronic kidney disease and in kidney transplant recipients in an effort to improve efficacy. The seroconversion rate after two vaccine doses is reduced, especially in kidney transplant recipients. Furthermore, although the seroconversion rate in chronic kidney disease patients is as high as in healthy subjects, anti-spike antibody titres are lower than in healthy vaccinated individuals, and these titres decrease rapidly. Although the vaccine-induced anti-spike antibody titre correlates with neutralising antibody levels and with protection against COVID-19, the protective prognostic significance of their titre is decreased due to the emergence of SARS-CoV-2 variants other than the Wuhan index virus against which the original vaccines were produced. Cellular immunity is also relevant, and because of cross-reactivity to the spike protein, epitopes of different viral variants confer protection against newly emerging variants of SARS-CoV-2. A multi-dose vaccination strategy is the most effective way to obtain a sufficient serological response. In kidney transplant recipients, a 5-week discontinuation period from antimetabolite drugs in concomitance with vaccine administration may also increase the vaccine's efficacy. The newly acquired knowledge obtained from COVID-19 vaccination is of general interest for the success of other vaccinations in chronic kidney disease patients.