The pathogen that causes COVID-19 has been designated as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 or SARS-2). It is widely speculated that SARS-CoV-2 has originated from the bat strains of coronaviruses. The spike glycoprotein (SGP) is the main component of the coronavirus envelope which plays important role in the entry of the virus into mammalian cells. In our earlier reports we have eluded to the presence of large peptide domains in the SGP that are highly conserved in the Sarbecovirus group. Many of the severe acute respiratory syndrome (SARS)–causing coronaviruses belong to this group. We now show that three large peptide domains of SGP are present in un-substituted forms in close to 100% of the Sarbecovirus strains. Most of the recently introduced mRNA vaccines employ the SGP as the target protein. Although the receptor binding domain of the SGP has evolved out and deviated significantly from that of the SARS and SARS-like viruses, the mRNA vaccines still have the potential to offer protection against the present as well as future SARS pandemics due to the presence of these three extraordinarily conserved polypeptide domains in the SGP molecule.