Introduction: Transplant recipients, due to their immunocompromised condition and often other associated risk factors, present a high risk of infection and organ rejection. The objectives of this work have been to assess the evolution of transplant recipients with covid-19 infection and the development of kidney injury or rejection, comparing the unvaccinated (UV) and vaccinated (V) against sars-cov-2.

Method: Descriptive, cross-sectional study with an analytical component in kidney transplant patients from our unit, with covid-19 infection, from March 2020 to February 2022. Statistical analysis: Excel 2010 program, includes medians, standard deviation, percentages, and t-test.

Results: 29.4% of the total number of transplant patients (60/204) presented covid-19 infection; 37 unvaccinated patients (UV) and 23 vaccinated patients (V), mean age of 50±11 years and transplant time of 137±99 months. Kidney function one-month post-covid: creatinine 2.3±1.5mg/dl in UV and 1.8±1.1mg/dl in V (p= 0.07). MDRD4 clearance: 44.9±20 ml/min/1.73m2 in UV and 38.7±22.8 ml/min/1.73m2 V (p=0.03). The resistance index: 0.73±0.11 in UV and 0.69±0.04 in V (p= 0.023). Proteinuria in both populations without significant changes. Evolution: In the UV, 17 mild cases, 6 moderate, and 14 severe; in V, 15 mild cases, 4 moderate and 4 severe cases. Severity index: Ferritin in UV, 1069.4±678.8 ng/ml and in V, 397±441 ng/ml (P 0.0000099). D-dimer, 629.8±700.5 ng/ml in UV and 333.5±501.5 ng/ml in V (p= 0.03) Hospitalization was 56.7% and 34.7% in unvaccinated and vaccinated, respectively, with an average of 5.2±7.6 days of hospitalization, requiring invasive mechanical ventilation, 35% (13 cases) in UV and 4 .3% (1 case) in V. Interstitial Pneumonitis due to covid-19 present in 28 unvaccinated and 10 vaccinated. Other complications: 2 activations of Cytomegalovirus; a case of Optic Nerve Neuritis; 23 cases of Bacterial pneumonia; 1 case of Pansinusitis; 3 cases of suspected kidney graft rejection. Mortality: 25% in UV (15/60 cases), and 1.6% (1/60 cases) in V.

Conclusion: Renal function had a significant deterioration in UV patients with respect to V one month after covid. The unvaccinated patients evolved worse than the vaccinated ones with higher rates of severity, hospitalization, assisted respiration and deaths, which shows the importance of complete vaccination in immunosuppressed patients, from their pre-transplant preparation. Close follow-up is vital for early detection of post-covid complications.