The COVID-19 puzzle: a global nightmare

In December 2019, WHO was informed with several unknown pneumonia cases and later it was found as highly contagious, transmittable and pathogenic viral infection. The novel coronavirus (nCoV-19) was firstly reported from Wuhan city in China. COVID-19 has raised the concern of the world since its emergence from China. The WHO has declared an ongoing COVID-19 outbreak as a pandemic. Till now 6,057,853 confirmed cases with 371,166 deaths have been reported from approximately 213 countries of the world. The aim of this study is to discuss all the aspects related to recently discovered novel coronavirus. The article, therefore, provides a comprehensive study on the genomic, epidemiological, social, clinical and environmental aspects of SARS-CoV-2. SARS-CoV-2 uses human ACE2 receptor as a ligand to bind and transmit its genome just like the SARS-CoV. The clinical symptoms of SARS-CoV-2 are very non-specific and include fever, sore throat, wheezing, rales, headache and rhinorrhoea with round-glass pulmonary opacifications shadowing in X-ray. Many antiviral drugs show efficacy but only in mild to moderate infection levels. Though efforts on development of SARS-CoV-2 vaccine have been started earlier as soon as the pandemic was emerged, till date no effective drug or vaccine has been validated with significant efficacy against the disease; therefore, there is a dire need to design effective vaccine against SARS-CoV-2. Multiple vaccine candidates are still in evaluation and exploratory stages on different clinical models with potential results on different animals and human models. mRNA-1273, ChAdOx1, Ad5-nCoV, INO-4800, LV-SMENP-DC and pathogen-specific aAPC are the most advanced and potential drug candidates against COVID-19. Recent studies have revealed any attractive vaccine candidates as promising therapeutic agents based on different strategies of vaccines. Here, the rationale of this review was also to provide an overview of the pathogenesis of the virus and summarize the updated potential vaccine candidates against SARS-CoV-2.