Browsing by Author "Ozturk, Hakki"

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Comparison of SARS-CoV IgG Responses in Hemodialysis Patients and Healthcare Workers After COVID-19 Vaccination
(Frontiers Media S.A., 2025) Ozturk, Hakki; Ozsoy, Metin; Tuna, Aysegul; Varlibas, Artuner; Cesur, Salih; Aksoy, Altan; Demir, Mehmet Emin
Aim: This study aimed to compare SARS-CoV-2 IgG antibody levels in hemodialysis (HD) patients and healthcare workers (HCWs) after COVID-19 vaccination and to identify factors influencing these levels. Materials and methods: A total of 193 participants were included: 104 HD patients and 89 age- and sex-matched HCWs as controls. All had completed a primary COVID-19 vaccination series (two doses of CoronaVac or BNT162b2) and a booster dose. SARS-CoV-2 anti-spike IgG was measured at least one month after the last vaccine dose using a commercial immunoassay (Abbott SARS-CoV-2 IgG II Quant, CMIA). Results in Arbitrary Units (AU/mL) were converted to WHO standard Binding Antibody Units (BAU/mL) (1 AU/mL = 0.142 BAU/mL). IgG titers >= 7.1 BAU/mL (equivalent to 50 AU/mL) were considered positive. Results: All participants had positive SARS-CoV-2 IgG antibodies. There were no statistically significant differences in IgG levels between HD patients and HCWs at any individual time interval (<3 months, 3-6 months, or >6 months) or in the overall mean titers (HD: 1259 +/- 1112 BAU/mL; HCW: 1002 +/- 765 BAU/mL; p = 0.216). No individual in either group had an IgG titer below 7.1 BAU/mL. Vaccine type, dialysis vintage, and presence of comorbidities did not significantly impact antibody levels. In the HCWs group, those vaccinated only with CoronaVac had significantly lower IgG levels than those receiving only BNT162b2 or a heterologous regimen (CoronaVac followed by BNT162b2). However, among HD patients, IgG levels did not differ by vaccine regimen. Conclusion: HD patients mounted a SARS-CoV-2 IgG antibody response comparable to that of healthy HCWs, with no participant falling below the positivity threshold. Dialysis duration and comorbid conditions did not significantly affect post-vaccination IgG levels. While HCWs who received only CoronaVac showed lower antibody titers than those who received BNT162b2 or a heterologous schedule, this difference was not observed in HD patients. These results suggest that COVID-19 vaccination elicits a robust humoral immune response in the HD population, underscoring the benefit of vaccination in this high-risk group.
Evaluation of Anti-Tetanus IgG Antibody Levels and Influencing Factors in Patients Undergoing Hemodialysis
(Frontiers Media Sa, 2025) Ozsoy, Metin; Ozturk, Hakki; Tuna, Aysegul; Varlibas, Artuner; Cesur, Salih; Aksoy, Altan; Demir, Mehmet Emin
Aim: This study aimed to assess anti-tetanus IgG antibody levels and identify determinants of inadequate tetanus immunity among maintenance hemodialysis (HD) patients. Methods: In this cross-sectional study, anti-tetanus IgG levels were measured by quantitative ELISA in 162 adult HD patients from two dialysis centers in Ankara, Turkey. Protective immunity was evaluated using both international (>= 0.1 IU/mL) and robust (>= 0.5 IU/mL) cut-offs. Demographic and clinical factors associated with immunity were analyzed by multivariate logistic regression. Results: Only 16.7% of HD patients achieved robust protection (>= 0.5 IU/mL), whereas 49.8% had minimal protection (>= 0.1 IU/mL). Protective immunity was independently associated with younger age (OR 1.07 per year; p = 0.004), shorter dialysis duration (OR 1.07; p = 0.030), male sex (female OR 2.92; p = 0.048), and recent booster vaccination within 10 years (OR 0.11; p < 0.001). Diabetes mellitus was not an independent factor. Conclusion: Most HD patients lacked durable tetanus immunity, particularly older females on long-term dialysis. The findings highlight the need for regular antibody monitoring, early revaccination, and structured booster programs to maintain adequate protection in this high-risk population.
Investigation of Hepatitis E Virus Seroprevalence and Risk Factors in Hemodialysis Patients
(Frontiers Media Sa, 2025) Ozturk, Hakki; Ozsoy, Metin; Tuna, Aysegul; Varlibas, Artuner; Cesur, Salih; Aksoy, Altan; Demir, Mehmet Emin
Background: Hemodialysis patients are at increased risk for hepatitis E virus (HEV) infection due to their immunocompromised status and frequent exposure to invasive medical procedures. HEV can lead to chronic infections and severe complications, particularly in high-risk populations. This study aimed to determine HEV-IgG seroprevalence among hemodialysis patients in Ankara, Turkey, and evaluate associated risk factors. Methods: A total of 160 hemodialysis patients from three private dialysis centers in Ankara were included in this prospective, cross-sectional study. Anti-HEV-IgG antibodies were detected using the ELISA method. Demographic characteristics and potential risk factors, including dialysis duration, comorbidities, blood transfusion history, drinking water source, dietary habits, and involvement in animal husbandry, were assessed via structured surveys. Statistical analyses were conducted using SPSS Version 22.0, with Pearson's chi-square and Fisher's exact tests applied to categorical variables. Logistic regression analysis was performed to identify independent risk factors for HEV seropositivity. Results: HEV-IgG seropositivity was detected in 42 patients (26.25%). Seroprevalence increased significantly with age, rising from 6.7% in patients under 55 years to 47.4% in those over 65 years (p < 0.001). Extended dialysis duration (>5 years) was also significantly associated with HEV seropositivity (p = 0.02). However, no significant associations were found between HEV seropositivity and gender, blood transfusion history, source of drinking water, consumption of raw meat, or involvement in animal husbandry (p > 0.05). Conclusion: The HEV-IgG seroprevalence among hemodialysis patients in Ankara was higher than previously reported rates in Turkey. Age and prolonged dialysis duration emerged as significant risk factors, underscoring the importance of screening and preventive strategies in this vulnerable population. Further multi-regional studies are needed to better understand HEV transmission dynamics and improve management strategies in hemodialysis patients.