#2600 INCIDENCE RATE, OUTCOMES, AND RISK FACTORS ASSOCIATED WITH COVID-19 INFECTION IN FULLY MRNA-VACCINATED HEMODIALYSIS PATIENTS
Authors: Rysyev Andriy , Stepanova Natalia , Ostapenko Tetyana , Snisar Lyudmyla , Khizhyna Anna , Filonov Vyacheslav , Marchenko Valeriya , Pyankovskyi Serhiy 
Published: June 2023

Abstract

Background and Aims
Despite the high efficacy of vaccines against coronavirus disease (COVID-19), some people continue to become infected with SARS-CoV-2 after vaccination. Older age, immunosuppression, and severe comorbidities are associated with the occurrence of COVID-19 and adverse outcomes in the general population of vaccinated patients. However, because of the above factors, hemodialysis (HD) patients may be at higher risk for postvaccination SARS-CoV-2 infection than the general population, and risk factors associated with COVID-19 in fully vaccinated HD patients have never been studied. The present study aimed to determine the incidence rate, outcomes, and risk factors for SARS-CoV-2 infection in fully vaccinated HD patients.

Method
In this multicenter case-control cohort study, we followed HD patients for 1 year after SARS-CoV-2 vaccination and compared incidence rates and outcomes of COVID-19 with unvaccinated patients selected by propensity score matching based on potentially confounding variables (age, diabetes, and dialysis vintage). Patients who had been fully vaccinated against COVID -19 with either Pfizer-BNT-162b2 or Moderna-mRNA-1273 vaccine and had at least one positive SARS-CoV-2 PCR test &gt; 14 days after the second dose were defined as cases. Unvaccinated HD patients who had not been infected with COVID-19 before study enrollment and had at least one positive test thereafter were defined as controls. The outcomes studied were COVID-19-related hospitalizations, oxygen maintenance, and death. Demographic data and routine blood tests (the last measurements before COVID -19) were analyzed as possible risk factors for COVID -19 infection in vaccinated HD patients. Data were presented as incidence rate or proportion and compared with the chi-square (χ2) test. Univariate logistic regression analysis was used to determine risk factors for SARS-CoV-2 infection after vaccination and presented as odds ratio (OR) and 95% confidence interval (CI).

Results
Among a total cohort of HD patients (n = 327) aged 52 ± 9.4 years with a dialysis vintage of 44 (21-76.6) months, 133 (40.7%) HD patients were fully vaccinated. During the 12-month follow-up period, the incidence rate of SARS-CoV-2 infection was significantly lower in the vaccinated group compared with the matched unvaccinated group: 0.29 (95% CI 0.18; 0.42) vs 0.59 (95% CI 0.46; 0.74) per patient-year (p &lt; 0.0001). Proportions of COVID-19-associated hospitalization (χ2 = 20.1, p &lt; 0.0001), oxygen demand (χ2 = 27.8, p &lt; 0.0001), and death (χ2 = 7.6, p = 0.004) were also significantly lower in the case group compared to unvaccinated matched controls. In risk factor analysis, older age, obesity, dialysis duration of more than 5 years, arterial hypertension, elevated C-reactive protein, anemia, and low levels of parathyroid hormone and high-density lipoprotein cholesterol were associated with postvaccination SARS-CoV-2 infection (Fig. 1).

Conclusion
Vaccinated HD patients had a significantly lower incidence of SARS-CoV-2 infection and associated adverse outcomes compared to the unvaccinated group. HD patients aged ≥ 65 years with Kt/V &lt;1.2, obesity, dialysis duration of more than five years, arterial hypertension, elevated C-reactive protein, and low levels of hemoglobin, parathyroid hormone, and high-density lipoprotein cholesterol had a higher risk of infection following vaccination.