How do the severe acute respiratory coronavirus 2 (SARS-CoV-2) and its variants escape the host protective immunity and mediate pathogenesis?

BACKGROUND: To protect the global population from the ongoing COVID-19 pandemic caused by the severe acute respiratory β-coronavirus 2 (SARS-CoV-2), a number of vaccines are currently being used in three dosages (i.e., along with the booster dose) to induce the immunity required to combat the SARS-CoV-2 and its variants. So far, several antivirals and the commercial vaccines have been found to evoke the required humoral and cellular immunity within a huge population around world. However, an important aspect to consider is the avoidance mechanism of the host protective immunity by SARS-CoV-2 variants. MAIN BODY OF THE ABSTRACT: Indeed, such an immune escape strategy has been noticed previously in case of SARS-CoV-1 and the Middle East Respiratory Syndrome coronavirus (MERS-CoV). Regarding the SARS-CoV-2 variants, the most important aspect on vaccine development is to determine whether the vaccine is actually capable to elicit the immune response or not, especially the viral spike (S) protein. SHORT CONCLUSION: Present review thus focused on such elicitation of immunity as well as pondered to the avoidance of host immunity by the SARS-CoV-2 Wuhan strain and its variants.