Introduction: To date, the world has experienced four waves of the Coronavirus disease- 19 (COVID-19) pandemic. Patients infected during the era of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant were the subject of this study. The objectives were to describe their clinical manifestations, explain their laboratory and radiological findings, conclude factors contributing to clinical outcomes, and evaluate treatment protocols. Methodology: Relevant data were collected retrospectively from records of patients admitted to six referral centers in four countries. Data included sociodemographic patterns, symptoms, associated comorbidities, physical examination, laboratory and radiologic findings, treatment received, and patient outcomes. Results: Data analysis identified symptomatology and variables related to acquisition and infection outcome. The most prevalent symptoms were cough (81.5%), body aches (74.1%), and fever (71.6%). Independent risk factors for mortality were age, vomiting, epigastric pain, diabetes, obesity, oxygen saturation less than 90%, leukocytosis, neutrophilia, lymphopenia, thrombocytopenia, elevated creatinine, high glucose level, lung ground glass opacities with consolidation, affection of four lobes and bilateralism. Neither d-dimer nor lactate dehydrogenase nor ferritin foretells death possibility. The efficacy of the medications used was convenient. Conclusions: Assessing the clinical features of different COVID-19 waves, identifying predictors of outcomes, and concluding the efficacy of treatment protocols provide insight into patients' responses and viral behaviors, which help in the proper diagnosis and treatment of subsequent surges..