Though SARS-COV-2 genome has a much lower mutation rate and genetic diversity than SARS, some of its mutations attract the special attention of scientists. Single amino acid mutation R408I in RBD can reduce the affinity of ACE2 receptor binding [115] that leads to a low or ineffective vaccine for the future epidemic. Effectively, sequence alignment showed that this 408R is strictly conserved in SARS-CoV-2, SARS-CoV. 408R located at the interface between RBD and ACE2, but positioned relatively far away from ACE2, does not have direct interaction with ACE2. 408R can form a hydrogen bond with the 90 N of ACE2. This hydrogen bond is suggested to contribute to the high binding affinity of ACE2 binding [115].