9. Conclusions
Because of structural similarity and binding to same host cell receptors, SARS-CoV-2 and SARS-CoV may potentially share similar disease pathogenesis and exhibit cross-immunity to some extent. The understanding of biological characteristics of SARS-CoV and technological advancement in vaccine production could make first-generation COVID-19 vaccine available very soon, though it may not be available to cater the current pandemic. There are about 7 or 8 SARS-CoV-2 antigenic candidates which could be employed for vaccine development. But there is a need of vigorous testing for immunogenicity, safety, efficacy, and level of protection conferred in the hosts. Hastening the deployment of first-generation vaccine for current pandemic could be achieved by propelling the nucleic acid based priming vaccines followed by boosters of protein based vaccines to curtail the mortality in high risk groups such as elderly persons and health care workers. Parallel to this, more potent and efficient second-generation vaccine production for future should be carried out to prevent disease spread, mortalities, and viral shedding. Another intriguing aspect of CoVs is that in every decade of 21st century there is a new major CoV epidemic viz . SARS in 2002, MERS in 2012, and now COVID-19. Such epidemics are expected in future too. Among CoVs S2 subunit is highly conserved and homologous which is a potential target for development of a pan-CoV vaccines after enhancing its immunogenicity and it can be used across all population worldwide and against divergent strains of CoVs. Thus, there is a need to mobilize the international funding agencies to support the development, manufacture, and stockpiling of CoV vaccines.