Investigation of IgG Titers in Hemodialysis Patients and Controls Following Administration of the COVID-19 Vaccine.

Introduction: End-Stage Renal Disease (ESRD) patients necessitate dialysis when kidney transplantation is not feasible. Hemodialysis patients exhibit higher mortality rates compared to the general population due to uremia and an increased burden of comorbidities. In this vulnerable population, defective innate and adaptive immunity contribute to infectious diseases being a leading cause of hospitalization and mortality. Given the COVID-19 pandemic and the potential for a diminished antibody response to the COVID-19 vaccine among dialysis patients, this study aimed to measure IgG antibody titers in this patient group following COVID-19 vaccination and compare them to healthy individuals.

Materials and methods: This cross-sectional study enrolled hemodialysis patients who had received a minimum of two doses of the COVID-19 vaccine within the past two to six months. Informed consent was obtained from the patients for antibody titer testing. Additional information was collected using a checklist. A control group consisting of individuals who had also received at least two doses of the COVID-19 vaccine was selected and matched to the patient group based on vaccine type, number of doses, and timing of administration. Relevant data for both groups were recorded in the checklist. IgG titers were measured using the indirect ELISA technique to quantify specific IgG against the Spike antigen in the serum samples of both patients and controls. A comparison of IgG titers between the two groups was conducted using SPSS version 26 software.

Results: The hemodialysis group comprised 44.1% males, while the control group consisted of 67.6% males. The mean age for the hemodialysis and control groups was 59.97±15.92 and 54.79±21.77, respectively. Underlying diseases were present in 76.5% of the hemodialysis group and 58.8% of the control group, with hypertension being the most common comorbidity in both groups. Sinopharm was the most commonly administered vaccine in both groups for both the first and second doses. Vaccine side effects were reported by 50% of hemodialysis patients and 17.6% of the control group. Furthermore, 55.9% of the hemodialysis group and 35.3% of the control group had a history of prior COVID-19 infection before vaccination. The positive IgG titer rates were 94% in the hemodialysis group and 91% in the control group, with no significant difference observed between the two groups (P<0.999). The relationship between positive IgG titers and group membership was not significant across other investigated variables.

Conclusion: The present study revealed no significant difference in IgG titers against the S1 antigen between hemodialysis patients and controls who had received a minimum of two doses of the COVID-19 vaccine. Furthermore, IgG titers were not associated with age, sex, underlying diseases, vaccine side effects, or behavioral parameters. In addition, an inverse correlation was observed between the duration since the last vaccine dose and the initiation of dialysis, and IgG titers.