Аңдатпа
Background: Although coronavirus disease 2019 (COVID-19) vaccination reduces severe acute disease, post-COVID-19 condition (PCC) remains a significant concern among vaccinated individuals. QazVac (QazCovid-in ® ), an inactivated whole-virion SARS-CoV-2 vaccine developed in Kazakhstan, has demonstrated efficacy against severe COVID-19; however, determinants of PCC following QazVac vaccination are not well characterized. This study aimed to identify demographic, clinical, and immunological factors associated with PCC among QazVac-vaccinated individuals. Materials and Methods: A cross-sectional study was conducted in Aktobe, Kazakhstan, including 90 QazVac-vaccinated individuals with PCC and 116 QazVac-vaccinated participants without PCC. Data on demographics, comorbidities, markers of acute COVID-19 severity, and immunological parameters (SARS-CoV-2 immunoglobulin G levels and lymphocyte subsets assessed by flow cytometry) were collected. Associations with PCC were examined using univariate and multivariable logistic regression analyses. Results: In the final multivariable model, polymerase chain reaction-confirmed SARS-CoV-2 infection was the strongest independent determinant of PCC (adjusted odds ratio [aOR] 28.8, 95% confidence interval [CI] 9.75–85.02; P < 0.001), whereas older age (aOR 1.04 per year, 95% CI 1.02–1.07; P = 0.002) and higher body mass index (BMI) (aOR 1.11 per kg/m², 95% CI 1.01–1.23; P = 0.036) remained independently associated. Chronic kidney disease (CKD) showed a strong but borderline association with PCC (aOR 5.87, 95% CI 0.98–35.05; P = 0.052), and sex was not independently associated after adjustment (men vs. women: aOR 0.49, 95% CI 0.20–1.17; P = 0.108). Conclusion: Despite QazVac vaccination, PCC occurs predominantly following breakthrough SARS-CoV-2 infection and is modified by age, BMI, and underlying CKD, alongside distinct humoral and cellular immune changes. These findings underscore the need for targeted postinfection monitoring in high-risk vaccinated individuals and support further investigation into immune mechanisms and vaccine strategies to mitigate long-term sequelae.