Post-quadri-vaccinal SARS-CoV-2 antibodies in Vietnamese patients with end-stage renal disease: A prospective cohort study.

Patients with chronic kidney disease are at high risk for severe coronavirus disease 2019 (COVID-19). Although vaccination offers protection, antibody titers in this population decline over time. This study measured SARS-CoV-2 spike protein IgG (anti-S) levels at 1 and 6 months after the 4th vaccine dose and identified factors associated with antibody decline in Vietnamese patients with end-stage renal disease receiving hemodialysis. A prospective cohort study was conducted on 87 end-stage renal disease patients undergoing hemodialysis at Can Tho General Hospital, Vietnam, after 4th dose of COVID-19 vaccine, from July 2022 to January 2023. The median anti-spike protein antibody (IgG anti-S) levels at 1 month (T1) after the 4th dose of COVID-19 vaccine in patients was 13559.0 AU/mL (7713.0-19608.0). After 6 months (T6), antibody levels decreased to 8197.0 AU/mL (4116.0-13793.0). Patients with multiple comorbidities and prolonged dialysis vintage were independent factors associated with lower antibody levels 6 months after the 4th dose of COVID-19 vaccine. All patients in our study had an immune response that produced IgG anti-S antibodies after receiving 4 doses of the COVID-19 vaccine. Median IgG anti-S concentration at 1 month was 13559.0 AU/mL (7713.0-19608.0), at 6 month was 8197.0 AU/mL (4116.0-13793.0). The more comorbidities and prolonged dialysis vintage the patients had, the lower the IgG anti-S concentration after 6 months.