The growing complexity of COVID-19 drug and vaccine candidates: challenges and critical transitions.

COVID-19 has nowadays affected almost all our societies and global health systems. The latest deadly pandemic has heavily influenced both life and livelihood worldwide. SARS-CoV-2 is the causative organism of COVID-19, that is spreading and infecting significantly higher compared to other coronavirus, due to its constant mutation characteristics. At present although several extensive clinical trials are ongoing, neither approved drug therapy nor any vaccine are available to safely fight SARS-CoV-2. However, a progressive race among numerous research groups to discover a radical cure for the COVID-19 is under way. This review aims to provide an updated insight of the current research, development and trials on repurposing existing drugs and preventive intervention for COVID-19, along with the related issues, complexities and challenges, especially after the observed high transmissibility lately.