If the S mutation site was in the MHC-like domain, the mutation enhanced the MHC decoy function. Then the human immune system hard to neutralize these MHC-like sites by producing antibodies. Otherwise, it would affect the normal MHC antigen presentation function by combing MHC and the antibodies. Based on this principle, we analyzed several significant variants that were now popular to determine the MHC-like enhanced region of the S protein.