Background: The assignment of mortality risk from SARS-CoV-2 virus (COVID-19) to vulnerable patient groups is an important step toward containment of the pandemic. Methods: A total of 760 patients with a positive molecular test for SARS-CoV-2 who were unvaccinated against COVID-19 were recruited between 1 January and 30 June 2021. Patients were grouped by age; sex; and common morbidities, such as atrial fibrillation, chronic respiratory disease, coronary disease, diabetes type II, neoplasia, hypertension and β-Thalassemia heterozygosity. As a primary endpoint, we assessed mortality risk from COVID-19, and as secondary endpoints, we considered clinical severity and need for Intense Care Unit (ICU) admission. Results: In multivariate analysis, male sex (p < 0.001, OR = 2.59), increasing age (p < 0.001, OR = 1.049), β-Thalassemia heterozygosity (p = 0.001, OR = 2.41) and chronic respiratory disease (p = 0.018, OR = 1.84) were identified as risk factors associated with mortality due to COVID-19. Moreover, male sex (p < 0.001, OR = 1.98), increasing age (p < 0.001, OR = 1.052) and β-Thalassemia heterozygosity (p = 0.001, OR = 2.59) were associated with clinical severity in logistic regression. Regarding ICU admission, the risk factors were identified as male sex (p = 0.002, OR = 1.99), chronic respiratory disease (p = 0.007, OR = 2.06) and hypertension (p < 0.001, OR = 5.81). Conclusions: An increased mortality risk from COVID-19 was observed for older age, male sex, β-Thalassemia heterozygosity and respiratory disease. Carriers of β-Thalassemia were identified as more vulnerable for severe clinical symptomatology, but there was no increased possibility for ICU admission. Readjustment of these findings to consider impacts of variant strains prevailing during the latest viral outbreak among vulnerable patient groups may offer timely relief from the pandemic.