Breakthrough infections following mrna sars-cov-2 vaccination in kidney transplant recipients

Abstract BACKGROUND AND AIMS The clinical effectiveness of COVID-19 vaccination in kidney transplant (KT) recipients is lower than in the general population. However, the evidence reported is limited so far. Our purpose is to analyze the characteristics and outcomes of a large series of KT with COVID-19 breakthrough infection and compare them with unvaccinated patients. As a secondary objective, we analyzed the evolution according to the type of mRNA vaccine administered. METHOD From April to October 2021, KT recipients with COVID-19, included in the Spanish Society of Nephrology COVID-19 Registry, were analyzed. Data regarding vaccination status and type of vaccine were collected and outcomes of unvaccinated patients were compared with fully vaccinated patients. Univariable and multivariable Cox proportional hazard regression analyses were assessed for independent risk factors of COVID-19-related death. To avoid bias as much as possible, a sensitivity analysis was done exclusively in hospitalized patients. RESULTS During the period of the study, 481 KT recipients with COVID-19 were included in the registry: 351 fully vaccinated and 130 unvaccinated. Age, gender, KT vintage, diabetes as primary kidney disease, induction and maintenance immunosuppression and anti-COVID therapy were similar between both groups. Clinical picture was similar between fully vaccinated and unvaccinated patients: 10% versus 15.4% remained asymptomatic (P = 0.100), 56.7% versus 58.5% developed pneumonia (P = 0.720) and 66.1% versus 63.8% were hospitalized (P = 0.640), respectively. Survival analysis showed no differences between groups: 21.7% of fully vaccinated patients and 20.8% of unvaccinated died (P = 0.776). In multivariable analysis, age (HR: 1.05, CI 95% 1.03–1.08, P < 0.001) and pneumonia (HR: 14.16, CI: 95% 5.02–39.88, P < 0.001) were independent risk factors for death, while vaccination status was not related to mortality. These results remained similar when we analyzed exclusively hospitalized patients (death rate in fully vaccinated patients 31.9% versus 31.3% in unvaccinated patients, P = 0.840). Regarding the type of mRNA vaccine, 213 patients were vaccinated with the mRNA-1273 vaccine (Moderna) and 161 with the BNT162b2 (Pfizer-BioNTech), showing no differences in any of baseline and treatment-related variables analyzed. Patients vaccinated with the mRNA-1273 vaccine showed a significantly lower mortality than those who received BNT162b2 (16.4% versus 28.8%, P = 0.002), maintaining this difference in the multivariable analysis (reference mRNA-1273 vaccine: HR: 0.52, CI: 95% 0.31–0.85, P = 0.010). CONCLUSION COVID-19 severity in KT patients has remained high and has not improved despite receiving two doses of an mRNA vaccine. The mRNA-1273 vaccine has shown higher clinical effectiveness than BNT162b2 in KT recipients with breakthrough infection, so it could be considered as the first option in these patients.