Clinical Effectiveness of SARS-CoV-2 Vaccination in Renal Transplant Recipients. Antibody Levels Impact in Pneumonia and Death

Abstract

Background. Few studies have described the clinical impact of anti–severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in renal transplant recipients (RTRs) in the context of omicron variant and the third vaccine dose. Antibody titer has been tried to relate to the prediction of outcomes related to SARS-CoV-2, but it results controversially in these populations. Methods. All patients with positive SARS-CoV-2 polymerase chain reaction followed at a RTRs reference center from March 15, 2020, to March 15, 2022, were considered for analysis. Cases were analyzed by vaccination status. Breakthrough cases were then analyzed by nonantibodies (<20 arbitrary unit [AU]/mL), low (20–100 AU/mL), and high antibody titers (>100 AU/mL) against SARS-CoV-2 spike protein. Outcomes included pneumonia and mortality. We used logistic regression multivariable to assess for confounders. Results. Among 186 RTRs with coronavirus disease 2019, 50.5% (n = 94) were vaccinated versus 49.5% (n = 92) unvaccinated. Of the vaccinated patients, 67.02% developed a high antibody titer (>100 AU/mL) but 14.89% achieved a low antibody titer and 18.08%. Pneumonia-free survival (day 20) was 95% in high antibody titer but 40% in unvaccinated RTRs. Survival in RTRs at day 60 was similar in the unvaccinated group compared with nonantibodies breakthrough cases (82%) but 92% in the low antibody titer group (relative risk, 0.027; 95% confidence interval, 0.002-0.479; P = 0.014). Only patients with >100 AU/mL showed a 100% survival on day 60 postinfection. Conclusions. Vaccinated RTRs who achieve at least a low antibody titer (>20 AU/mL) had better results in terms of pneumonia and mortality than unvaccinated RTRs. Antibody titer >100 AU/mL associate with even better results than patients with lower antibody titers.

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

“…However, conflicting results were reported specifically in KTRs, which is a vulnerable patient group at high risk of adverse outcomes after SARS-CoV-2 infection. Several studies demonstrated lower immunogenicity after COVID-19 vaccination [ 4 , 26 , 27 , 28 , 29 , 30 ], but only a few studies investigated whether vaccination is effective in lowering COVID-19 incidence and severity in KTRs [ 31 , 32 ]. Hamm et al [ 33 ] showed the protective effects of COVID-19 vaccination in a national registry study from Denmark that included 1428 solid organ transplant recipients, of whom the majority were KTRs.…”

“…Concerns remain that another, more pathogenic SARS-CoV-2 variant will become dominant or that another new pathogenic virus will circulate in the near future for which large-scale (booster) vaccinations will be necessary. An important lesson we can learn from this study is that, in that case, the aim of vaccination should be to reach an antibody level as high as possible to prevent infection and severe disease in this vulnerable patient group and not just reaching seropositivity, as is emphasized in most current studies [ 31 , 32 , 49 , 50 ]. For future vaccinations, it should therefore be considered that KTRs do not follow the routine national vaccination programs, but a personalized vaccination scheme instead, based on antibody levels measured at a set time after vaccination.…”

Prevention and treatment strategies for kidney transplant recipients in the context of long-term existence of COVID-19

“…Rodríguez-Cubillo et al (111) also reported that compared with unvaccinated KTRs, vaccinated KTRs with at least low antibody titers (>20 AU/mL) exhibited improved outcomes in relation to pneumonia and mortality rates. Furthermore, patients with antibody titers >100 AU/mL had even better outcomes compared with those with lower antibody titers.…”

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

“…Despite the less robust response in SOTRs than the general population, evidence has shown that vaccination still provides significant protection for SOTRs and reduced mortality, in the context of evolving COVID variants [ 19 , 20 , 21 ]. Antibodies produced by COVID-19 vaccination have demonstrated associations with the pneumonia severity and mortality in renal transplant recipients during the Omicron wave; even with lower titers than in the non-immunocompromised patient population, outcomes are better than in the unvaccinated population and are the best in those who achieved an antibody concentration of >100 AU/mL [ 22 , 23 ].…”