Procedures
VESICULAR STOMATITIS, MAY, VIRUS
In May 2022, 200 eligible participants were randomly assigned to receive one dose of Ad5-nCoV (Convidecia, 0.5 mL of 5 × 10Blood samples were collected from each participant at baseline, before participants received the fourth dose of vaccination and again 6 months later, in December 2022. A commercial anti–SARS-CoV-2 RBD IgG ELISA kit (Vazyme Medical Technology, Nanjing, China) was used to measure the wild-type SARS-CoV-2 Receptor Binding Domain (RBD)-specific IgG response. The Reed–Muench method was also used to assess the levels of neutralizing antibody against the Omicron BA.4/5 subvariant using a pseudovirus-neutralization test, which consisted of a vesicular stomatitis virus pseudovirus system that expresses the spike glycoprotein (50% neutralization titer).In March 2023, after the pandemic and approximately 10 months after the fourth vaccination dose, the participants were followed up by telephone to collect information on breakthrough infection with SARS-CoV-2.