Vaccination coverage and its association with COVID-19 morbidity and mortality in Primorje-Gorski Kotar County

Introduction. The COVID-19 pandemic remains a global challenge despite extensive vaccination ef- forts. Although vaccination coverage has increased, coverage varies by population group, affecting hos- pitalization and mortality rates. Understanding the distribution of immunization coverage and its asso- ciation with severe disease outcomes is essential for public health planning.Aim. To analyze the association between COVID-19 vaccination status, hospitalizations and mortal- ity among adult residents of Primorje-Gorski Ko- tar County admitted to the Rijeka Clinical Hospital Center. Specific objectives included assessing the distribution of vaccinations by gender and age, the proportion of vaccinated persons among hospitalized patients and the proportion of vaccinated persons among those who died from COVID-19 between De- cember 27, 2020 and March 27, 2022.Methods. This retrospective study included 6,025 adult patients admitted with a confirmed COVID-19 diagnosis (ICD-10 code U07.1: COVID-19, virus iden- tified). The data were obtained from the Integrated Hospital System of the Clinical Hospital Center Rijeka and the Croatian Institute of Public Health.Results. Among hospitalized patients, men account- ed for 57.8% of cases. Vaccination coverage was higher in persons aged ≥65 years than in younger patients. Unvaccinated patients were hospitalized more frequently (50.19%) than vaccinated patients (44.9%). Mortality was significantly higher in unvac-cinated patients (1.36%) than in vaccinated patients (0.2%). The statistical analysis confirmed a signifi- cant correlation between vaccination status, hospi- talization and mortality.Conclusion. The results suggest that vaccination coverage was higher in individuals aged ≥65 years, while hospitalization and mortality rates were higher in unvaccinated patients. A statistically significant association was found between vaccination status and severe COVID-19 outcomes; however, causality cannot be established. Public health efforts should focus on maintaining high vaccination coverage, counteracting vaccination fatigue and ensuring ac- cess to booster vaccinations, especially for high-risk groups.