Abstract

At the end of 2019, there was a global pandemic jeopardizing the lives of millions of people, with reports on the spread of novel coronavirus (nCoV-2019). COVID-19 or the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated from bats and was transmitted to humans through an unknown source in Wuhan city located in China and spread across the globe in early 2020. The nCoV-19 uses its spike glycoprotein receptor to bind to the host cell angiotensin-converting enzyme 2 (ACE2) sites to launch a combination of events leading to server acute respiratory syndrome. In the past 100 years, the COVID-19 pandemic is the most destructive and life-threatening disease affecting the lives of millions of people after the Spanish flu. Hence, it requires a speedy measure to curtail the spread and combat the death rates. As it is said, vaccines are found to be a commendable strategy to alleviate the viral strains. The data required for the vaccine development, including the whole genome and protein sequence of SARS-CoV-2, were made available, which enabled numerous researchers and scientists across the countries to develop multiple vaccines for prophylactic and treatment of COVID-19. All these vaccines are in various stages of clinical trials. To date, globally, only 115 vaccine candidates have been developed, out of which 78 were found to be active and 37 yet to be confirmed. Vaccine development to prevent SARS-CoV-2 has potential hurdles where regulatory and medical decisions are taken based on the ratio between benefit and risk factors. Data on the specific SARS-CoV-2 antigen(s) used in vaccine development are highly limited in public resources. The vaccine developed mainly aimed to induce neutralizing antibodies against the viral spike (S) protein, preventing uptake via the human ACE2 receptor. However, it is unclear how different forms and/or variants of the S protein used in different vaccine candidates relate to each other or the genomic epidemiology of the disease. The most advanced candidates have recently moved into clinical development, including mRNA-1273 from Moderna, Ad5-nCoV from CanSino Biologicals, and INO-4800 from Inovio. Numerous other vaccine developers have indicated plans to initiate human testing in 2020. In this review, we focus mainly on the development of the SARS-CoV-2 vaccine using recombinant technology.