Author: Hoque et al. Summary: The aim of the study was to assess the antibody response to the ChAdOx1-nCoV vaccine in individuals who were not previously infected by COVID-19. All people aged 18-65 years who received their first vaccination with ChAdOx1-nCoV from March to May 2021 were approached for inclusion. Individuals with sufficient antibody titers against SARS-CoV-2 infection before vaccination were considered previously infected and were excluded from the analysis. We observed viral spike protein RBD-S1-specific IgG antibody levels at day 28 of the first dose of vaccination and day 14 of the second dose of vaccination (74 days from