To our knowledge, this is the first study showing that mAbs targeting the S2 domain of SARS-CoV-1 can cross-react with SARS-CoV-2 and this observation is consistent with the high sequence conservation in the S2 subunit. The ability of these antibodies, particularly 1A9, to detect SARS-CoV-2 S protein in indirect and sandwich ELISAs demonstrate their utility for detection of SARS-CoV-2 infections in a public health setting. Whether or not the current sensitivity of these antibodies are sufficient for robust detection of SARS-CoV-2 infections in a clinical setting and how they compare to existing PCR-based detection remains to be determined. Successful development of these antibodies into a point of care diagnostic kit will provide a complementary approach to existing detection methods. Besides the mAbs characterised here, several other mAbs have been reported to bind to epitopes in the S2 subunit of SARS-CoV-1 [31-33]. Thus, it will be important to determine if these mAbs can also cross-react with SARS-CoV-2.