Association Between Homologous and Heterologous COVID-19 Vaccine Regimens and Doses and Mortality in Hemodialysis Patients: A Nationwide Cohort Study from Thailand

Background: During the COVID-19 pandemic, Thailand prioritized hemodialysis patients for vaccination. Due to limited supply, heterologous regimens were used. This study evaluates the mortality rate and risk factors in hemodialysis patients who received heterologous versus homologous vaccine regimens. Methods: We retrospectively reviewed data of hemodialysis patients in Thailand from January 2021 to December 2022, using data from the Department of Medical Sciences, Ministry of Public Health, and Thailand Renal Replacement Therapy Registry. Mortality was defined as death within 30 days of a positive RT-PCR or rapid antigen test for SARS-CoV-2. Multivariate logistic regression was used to identify mortality risk factors. Results: The associated risks of mortality in hemodialysis patients with COVID-19 were female sex, age ≥ 50 years, diabetes, and BMI ≥ 25.0 kg/m2. Regarding vaccination regimens, the inactivated–Viral vector–mRNA regimen was associated with lower mortality compared with the mRNA–mRNA regimen (OR 0.29, 95% CI 0.08–0.99). In contrast, no vaccination (OR 16.95, 95% CI 7.86–36.54) and single-dose vaccination with inactivated vaccine (OR 17.54, 95% CI 7.01–43.88) or Viral vector vaccine (OR 20.74, 95% CI 9.38–45.86) were associated with markedly higher mortality risk. Conclusion: The inactivated–Viral vector–mRNA vaccine regimen was associated with a decreased mortality risk among this population.