| Description |
This is a multicenter, partially randomized, platform trial aims to evaluate the Effectiveness of a COVID-19 booster vaccination in adults aged 18 years and older predominantly with hybrid immunity against COVID-19, through a six-month surveillance period. Eligible participants were individuals aged 18 years and older, including those over 60 years of age and individuals with underlying medical conditions. Eligibility required an interval >/=4 months after the previous SARS-CoV-2 infection or confirmation of never having been infected, as well as >/=6 months since the last COVID-19 vaccination. Exclusion criteria for the vaccine groups included individuals exhibiting suspected COVID-19 symptoms on the day of enrollment, positive results on antigen rapid tests for SARS-CoV-2, having already completed a second COVID-19 booster immunization, a history of severe adverse reactions or anaphylaxis related to vaccination, and pregnant or lactating women. For the control group, the exclusion criteria were identical to those for the vaccine groups, with the exception of not having a history of severe adverse reactions or anaphylaxis related to vaccination. For COVID-19 endpoint cases with cycle threshold values below 32, nucleic acid samples underwent sequencing via the next-generation sequencing technology for variant typing of SARS-CoV-2. |
