COVID-19: An overview of the current pharmacological interventions, vaccines, and clinical trials

Abstract

COVID-19, the greatest public health emergency of the 21st century, has affected 215 countries and territories around the world resulting in 15,151,738 confirmed cases and 621,121 deaths. The outbreak has continued at breakneck pace despite stringent public health measures, ravaging the global economy and causing profound human casualties. Vaccination is currently the best bet for the prevention of COVID-19. Still, in its absence, there has been considerable interest in repurposing existing therapeutic agents to reduce the severity of the illness and ease the burden on the already strained healthcare systems. This review outlines the current evidence regarding proposed treatments- experimental or repurposed, for COVID-19, and gives an insight into the clinical trial landscape for drugs as well as vaccines.

Keywords: COVID-19; Clinical trials; Coronavirus; Drugs; SARS-CoV-2; Vaccines.

Graphical abstract

Fig. 1

Diagrammatic representation of the structure of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The figure represents the viral structure of SARS-CoV-2. The spike glycoprotein (S protein) confers a crown like appearance to the virus, hence the name ‘Coronavirus’. The S protein mediates the binding of the virus to cellular receptors. The role of hemagglutinin-esterase (HE) in Coronaviruses is poorly understood but it is reported to influence virion attachment in other viruses.

Fig. 2

Ecological origin and transmission of different species of Coronaviruses. This schematic representation illustrates the ecological origin, different animal hosts, and the subsequent transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 to the human population, eventually resulting in the three major epidemics/pandemic of the 21st century.

Fig. 3

Schematic representation of the entry of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) into host cell, its viral lifecycle and potential drug targets. The above-mentioned figure depicts the viral processing of SARS-CoV-2 within host cells. S protein has a major role in binding of the virus to the host receptor cells. It attaches itself to the ACE2 receptor of the human host cell, leading to the release of the viral RNA into the host cell which triggers a cascade that ultimately results in respiratory infection. Select repurposed drugs and their target sites of action are also represented in this schematic. ACE2: angiotensin-converting enzyme 2; S protein: spike protein; TMPRSS2: type 2 trans-membrane serine protease and IL-6: interleukin 6.