Methods
Pre- and post-vaccination sera from SARS-CoV-2 naïve healthy subjects who received three doses of the mRNA vaccine (BioNTech, BNT) or the inactivated vaccine (CoronaVac, CV) were used to monitor the level of cross-reactive antibodies raised against other human coronaviruses by enzyme-linked immunosorbent assay. In comparison, convalescent sera from COVID-19 patients with or without prior vaccination history were also tested. Pseudoparticle neutralization assay was performed to detect neutralization antibody against MERS-CoV.