After infection with SARS-CoV-1, patients start to produce SARS-specific IgG antibody in the second week, which persists for a long time31,32. Even after 210 days after symptom onset, neutralizing viral antibodies (anti-viral IgG) are still detectable in recovered SARS patients33. It is believed that the Spike protein and nucleocapsid protein play a central role in the antibody production31,32,34. Research has focused on developing vaccines and therapeutics targeting the Spike protein35,36 and the nucleocapsid protein37. However, our findings indicate that people are unlikely to develop long-lasting neutralizing antibodies to SARS-CoV-2 after SARS-CoV-2 infection. Cross-reactive antibodies in convalescent SARS patients' sera can neutralize other human betacoronaviruses40, as those viruses share a significant B-cell epitope overlapping the heptad repeat-2 region of the Spike protein. SARS-CoV-2 also belongs to betacoronaviruses. However, no individuals or populations had shown explicit immunity to SARS-CoV-2 and every human being in the world was susceptible to this virus before it first jumped from wild animals to humans. It might be due to the dramatic differences between SARS-CoV-1 and SARS-CoV-2 in the receptor-binding region of Spike protein and the key amino acid residues involved in the interaction with human ACE2