A prospective observational study for justification, safety, and efficacy of a third dose of mRNA vaccine in patients receiving maintenance hemodialysis

Abstract

The level of protection achieved by the standard two doses of COVID-19 mRNA vaccines in patients receiving maintenance hemodialysis (MHD) remains unclear. To study this we used the French Renal Epidemiology and Information Network (REIN) Registry to compare the incidence and severity of 1474 cases of COVID-19 diagnosed in patients receiving MHD after none, one or two doses of vaccine. Vaccination significantly reduce COVID-19 incidence and severity, but 11% of patients infected after two doses still died. Lack of vaccinal protection in patients naïve for SARS-CoV-2 could be due to defective Tfh response [38% of patients with negative spike-specific CD4⁺ T-cell interferon gamma release assay] and failure to generate viral neutralizing titers of anti-spike receptor binding domain (RBD) IgGs (63% of patients with titer at or under 997 BAU/ml, defining low/no responders) after two doses of vaccine. To improve protection, a third dose of vaccine was administered to 75 patients [57 low/no responders, 18 high responders after two doses] from the ROMANOV cohort that prospectively enrolled patients receiving MHD vaccinated with BNT162b2 (Pfizer). Tolerance to the third dose was excellent. High responders to two doses did not generate more anti-RBD IgGs after three doses but had more side effects. Importantly, 31 (54%) of low/no responders to two doses reached neutralizing titers of anti-RBD IgGs after three doses. A positive interferon gamma release assay and/or suboptimal titer of anti-RBD IgGs after two doses were the only predictive variables for response to three doses in multivariate analysis. Thus, the standard scheme of vaccination insufficiently protects patients receiving MHD. Anti-RBD IgG and specific CD4⁺ T-cell response after two doses can guide personalized administration of the third dose, which improves the humoral response of SARS-CoV-2-naïve patients receiving MHD.

Keywords: BNT162b2; COVID-19; SARS-CoV-2; hemodialysis; mRNA vaccine.

Graphical abstract

Figure 1

Severity of coronavirus disease 2019 (COVID-19) in patients on maintenance hemodialysis (MHD) according to their vaccination status. (a) Flowchart of the epidemiologic study conducted through the Renal Epidemiology and Information Network (REIN) network. (b) Cumulative incidence of the cases of COVID-19 that occurred over the study period in patients on MHD before vaccination or up to 10 days after the first dose (Not vacc, black curve), from 10 days after the first dose to 10 days after the second dose (1D, red curve), or more than 10 days after the second dose of vaccine (2D, green curve). Log-rank test; ∗∗∗∗P < 0.0001. (c) Severity of COVID-19 was color coded and the distribution was compared between the groups of patients on MHD defined according to their vaccination status. Chi-square test; ∗∗∗∗P < 0.0001. Asympto, asymptomatic; Not vacc, not vaccinated.

Figure 2

Flowchart of the Response of Hemodialyzed Patients to COVID-19 Vaccination (ROMANOV) prospective study. 2Ds, 2 doses; 3Ds, 3 doses; COVID-19, coronavirus disease 2019; MHD, maintenance hemodialysis.

Figure 3

Comparison of the immune responses of patients on maintenance hemodialysis (MHD) and healthy volunteers (HVs) after 2 doses (2Ds) of BNT162b2. Spike-specific cellular and humoral immune responses were evaluated 10 to 14 days after the 2D of vaccine in the circulation of 77 patients on MHD (circles; among which 14 had a previous history of coronavirus disease 2019, black circles) and 30 HVs (triangles; among which 4 had a previous history of coronavirus disease 2019, black triangles). (a,b) Enumeration of spike-specific CD8+ T cells by the activation-induced markers technique. (a) Gating strategy is shown on representative flow cytometry profiles. (b) Histogram showing individual values for HVs and patients on MHD. (c,d) Evaluation of viral neutralization capacity of the serum by in vitro functional assay. (c) Schematic representation of the methodology. (d) Histogram showing individual values for HVs and patients on MHD. (e,f) Enumeration of spike-specific CD4+ T follicular helper (Tfh) cells. (e) Gating strategy is shown on representative flow cytometry profiles. (f) Histogram showing individual values for HVs and patients on MHD, the latter being distributed in 2 groups (Neutral[+] or Neutral[−]) according to the viral neutralization capacity of their serum. Mann-Whitney U test; not significant (NS), P > 0.05; ∗P ≤ 0.05; ∗∗P < 0.01; ∗∗∗∗P < 0.0001. (g) The relation between the titers of anti–receptor binding domain (RBD) IgG measured in antigen-binding assay and the viral neutralization capacities evaluated in the in vitro functional assay shown in c was analyzed by linear regression. The threshold of anti-RBD IgG titer (997 binding arbitrary units [BAU]/ml) above which all sera had viral neutralization capacity is indicated by a vertical dashed line and was used to defined high responders (High-R) versus low or no responders (Low- or no-R) to 2Ds of vaccine. (h) The relation between the result of spike-specific CD4+ T-cell interferon-γ release assay (IGRA) and the percentage of spike-specific CD4+ Tfh cells enumerated as shown in e was analyzed by linear regression. FSC-A, forward scatter area; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

Figure 4

Reactogenicity to the third dose (3D) of mRNA vaccine in patients on maintenance hemodialysis (MHD). (a) Proportion of patients on MHD who developed local and systemic adverse events after the second dose (2D) and the 3D of vaccine are represented. Severity of the adverse event is color-coded (0–4) according to the scale detailed in the Methods section. (b) The number and the severity of local and systemic adverse events that occurred after the 2D and 3D of vaccine are compared. Chi-square test. (c) Proportion of patients on MHD who developed local and systemic adverse events after the 3D of vaccine according to the viral neutralization capacity of their serum after the 2D (high: neutralization+ vs. low or no: neutralization−). (d) The number and the severity of local and systemic adverse events that occurred after 3D of vaccine were compared between patients who were high responders and those who were low or no responders. Chi-square test. ∗∗∗P < 0.0001. NS, not significant.

Figure 5

Evolution of anti–receptor binding domain (RBD) IgG titers and the results of spike-specific CD4+ T-cell interferon-γ release assay (IGRA) between the second dose (2D) and the third dose (3D) of vaccine in patients on maintenance hemodialysis (MHD). (a–c) Anti-RBD IgG titers expressed in binding arbitrary units (BAU/ml) were measured 10 to 14 days after the 2D and 3D of vaccine. Upper dashed line represents the threshold (997 BAU/ml) above which all sera have viral neutralization capacity. This limit was used to define high versus low or no responders to the 2D. Lower dotted line indicates the limit of detection of the assay. (a) Results of the whole cohort of patients on MHD are plotted. (b,c) Evolution of anti-RBD IgG titers between the 2D and 3D of vaccine were compared for high responders (n = 18; b) and low or no responders (n = 57; c) only. Wilcoxon test. (d–f) Result of spike-specific CD4+ T-cell IGRA were measured 10 to 14 days after the 2D and 3D of vaccine. Lower dashed line indicates the limit of positivity of the assay. (d) Results of the whole cohort of patients on MHD are plotted. (e,f) Evolution of the results of spike-specific CD4+ T-cell IGRA between the 2D and 3D of vaccine were compared for high responders (n = 18; e) and low or no responders (n = 57; f) only. Wilcoxon test. The proportion of positive IGRA is indicated in the pie chart. (g) Forest plot of the results of the multivariate analysis conducted to identify the variables independently associated with the generation of anti-RBD IgG titers ≥997 BAU/ml after the 3D. (h) The proportion of patients on MHD that generated anti-RBD IgG titers ≥997 BAU/ml after the 3D is shown according to the presence of anti-RBD IgG and the result of spike-specific CD4+ T-cell IGRA after the 2D. Chi-square test. NS, not significant: P > 0.05; ∗P ≤ 0.05; ∗∗∗∗P < 0.0001. CI, confidence interval.