Waning of SARS-CoV-2 Vaccine-Induced Immune Response over 6 Months in Peritoneal Dialysis Patients and the Role of a Booster Dose in Maintaining Seropositivity.

INTRODUCTION: Although lower than general population, newly developed SARS-CoV-2 vaccines generate immune responses in end-stage kidney disease patients. However, the persistence of immune responses in the long term is not known yet. This study aimed to evaluate humoral immune responses in peritoneal dialysis (PD) patients over 6 months and to analyze the effects of the booster dose. METHODS: Humoral immune responses of PD patients were measured after initial SARS-CoV-2 vaccinations and after 6 months following initial vaccinations. Immune responses were compared between patients who received and did not receive booster doses. PD patients were compared with 41 hemodialysis (HD) patients and 61 healthy controls. Humoral immune responses were measured by a commercial test that detects antibodies toward the receptor-binding domain of the spike protein of SARS-CoV-2. RESULTS: Twenty PD patients were evaluated over 6 months. The initial seropositivity rate was 90.9% with inactivated vaccine and 100% with mRNA vaccine. Seropositivity decreased to 44.4% after 6 months, and a booster dose helped in maintaining the 100% of seropositivity (p = 0.005). Magnitude of humoral response at the 6th month was also higher in patients who received the third dose (1,132.8 ± 769.6 AU/mL vs. 400.0 ± 294.6 AU/mL; p = 0.015). Among patients who did not receive the third dose, those who got mRNA vaccine could maintain higher seropositivity than others who got inactivated vaccine (75% vs. 40% for PD, 81.8% vs. 50% for HD). Seropositivity and antibody levels were similar for PD and HD patients after 6 months (p = 0.24 and 0.56) but lower than healthy controls (p = 0.0013). CONCLUSION: SARS-CoV-2 vaccine-induced antibody levels and seropositivity of PD patients significantly fall after 6 months. A booster dose after around 3 months following initial immunization might help in maintaining seropositivity.

Intraperitoneal vancomycin-induced immune thrombocytopenia.

Vancomycin is one of the drugs used in the peritonitis treatment regimen of peritoneal dialysis patients. Intraperitoneal route is generally preferred to provide rapid elimination of infective agents. Systemic toxicities of certain drugs after intraperitoneal administration are not very clear. The same also applies to vancomycin, although it has a considerable amount of systemic absorption after intraperitoneal administration. We herein report a case of severe thrombocytopenia, which was seen during the treatment of a peritonitis attack in a peritoneal dialysis patient. Culture studies revealed methicillin resistant staphylococci as the causative agent and the patient received intraperitoneal vancomycin per sensitivity analysis. Thrombocyte levels dropped abruptly to 3,900/µl after 10 days of vancomycin treatment. Clinical criteria pointed out to vancomycin-related immune thrombocytopenia. Platelet levels did not recover with initial dexamethasone treatment and platelet transfusions. In the meantime, the clinical course was also complicated with intracranial bleeding. Intravenous immunoglobulin treatment was applied and dexamethasone was switched to high-dose methylprednisolone. This latter treatment generated a response and platelet levels gradually increased to normal levels. The patient could be discharged without any sequelae. There have been two previous intraperitoneal vancomycin-related immune thrombocytopenia cases in the literature. Previous cases were reviewed, and the present case was given in comparison with the previous cases.

Antibody responses to the SARS-CoV-2 vaccines in hemodialysis patients: Is inactivated vaccine effective?

INTRODUCTION: Vaccines generally have reduced effectiveness in hemodialysis patients and a similar condition may also apply for the SARS-CoV-2 vaccines. The aim of this study was to analyze humoral responses of hemodialysis patients to SARS-CoV-2 vaccines. METHODS: Eighty-five maintenance hemodialysis patients who received either inactivated or mRNA SARS-CoV-2 vaccines were investigated. Antibody levels were measured by a commercial antibody kit, which detected antibodies toward receptor binding domain of the SARS-CoV-2 spike protein. Comparative analyzes were carried between vaccine groups and with a control group of 103 healthy volunteers. RESULTS: Seropositivity rate and antibody levels were significantly lower in hemodialysis patients who received inactivated vaccine (p = 0.000). While mRNA vaccine had better immunogenicity, both vaccines protected from symptomatic infection when seropositivity was achieved. DISCUSSION/CONCLUSION: When used in the same dose with the general population, inactivated SARS-CoV-2 vaccines generate reduced humoral response in hemodialysis patients. mRNA vaccines have better immunogenicity in this group.