**Background:** The COVID-19 pandemic, caused by SARS-CoV-2, was first identified in Wuhan, China, in December 2019 and rapidly spread globally, leading to millions of deaths and severe economic repercussions. This comprehensive review aims to synthesize the vast literature on COVID-19, covering its etiology, epidemiology, pathogenesis, clinical symptoms, diagnostics, histopathologic findings, consequences, therapies, and vaccines, including long-term effects and associated myths. The review is intended to provide medical practitioners with a better understanding of the fundamental sciences, clinical treatment, and prevention of COVID-19, incorporating data available up to May 2023.
**Methods:** The authors analyzed a wide range of published data since the beginning of the pandemic to compile this narrative review. They examined core concepts including etiology, epidemiology, pathogenesis, clinical symptoms, diagnostics, histopathologic findings, consequences, therapies, and vaccines. The review also includes information on long-term effects and myths associated with COVID-19 therapeutics. The paper presents a comprehensive assessment of SARS-CoV-2 virology, vaccines, medicines, and significant variants identified during the pandemic.
**Key Results:** The review details the emergence of SARS-CoV-2 variants, including Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529), with Omicron being the most recent variant of concern as of the review date. The economic burden of COVID-19 is substantial, with direct medical costs in the US estimated to range from $163.4 billion (if 20% infected) to $654.0 billion (if 80% infected). The review highlights that age is the strongest risk factor for severe COVID-19, with the risk of death 340 times higher in those aged 85 years or older compared to individuals aged 18-29 years. The pathophysiology involves three phases: early infection, pulmonary phase, and hyperinflammation phase, with about 30% of patients progressing to the hyperinflammation stage. Histopathological findings include diffuse alveolar damage in 87% of patients in one autopsy study, and pulmonary thromboembolism in 42% of lungs. The review covers organ system manifestations, including cutaneous, cardiac, hematological, renal, pulmonary, gastrointestinal, hepatic, neuropsychological, and ocular manifestations. For therapeutics, the review discusses antivirals (remdesivir, Paxlovid, molnupiravir), antibody products (bamlanivimab/etesevimab, bebtelovimab, casirivimab/imdevimab, sotrovimab, tixagevimab/cilgavimab), immunomodulators (corticosteroids, IL-6 inhibitors, JAK inhibitors), and anticoagulation. The WHO has granted emergency use listing for 11 vaccines, including mRNA vaccines (Pfizer/BioNTech, Moderna), viral vector vaccines (AstraZeneca, Janssen), and inactivated vaccines (Sinopharm, Sinovac). The review also addresses COVID-19 in special circumstances (immunocompromised, pregnancy, HIV/AIDS), mental health impacts, and long-term effects (Long COVID), noting that fatigue is seen in more than 50% of patients with Long COVID.
**Clinical Implications:** This comprehensive review serves as a valuable resource for medical practitioners, consolidating a vast amount of information on COVID-19. It emphasizes the importance of understanding the evolving nature of the virus, the effectiveness of vaccines in reducing disease severity, and the need for continued surveillance and adaptation of treatment strategies. The review underscores that while the WHO has declared COVID-19 no longer a global health emergency, ongoing vigilance is required due to the emergence of new variants. The detailed coverage of organ system manifestations, therapeutic options, and special populations provides clinicians with a practical guide for managing COVID-19 patients. The review also highlights the significant economic burden and the importance of addressing mental health and long-term complications associated with the disease.