Sonora Quest is performing a test kit manufactured by EUROIMMUN, a PerkinElmer company. The assay kit package insert6 states that in the validation of the ELISAs, no cross-reactions to antibodies against worldwide-distributed coronaviruses were detected. Cross-reactions with antibodies against the closely related SARS-CoV(-1) and other known human coronaviruses (HKU1, NL63, OC43, or 229E) cannot be completely excluded. However, the specificity of the SARS-CoV-2 IgG immunoassays (ELISA and CMIA) is approximately 99%. Manufacturers6 tested panels of samples from pre-COVID times (2010, 2017, and 2019), with less than 1% samples showing positive results. These findings suggest that antibodies against SARS-CoV and other coronaviruses are not commonly found in the general public.