An Observational Prospective Cohort Study of Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection of an Aerosolized, Inhaled Adenovirus Type 5-Vectored Coronavirus Disease 2019 Vaccine Given as a Second Booster Dose in Guangzhou City, China

Using a prospective, observational cohort study during the post-dynamic COVID-zero wave in China, we estimated short-term relative effectiveness against Omicron BA.5 infection of inhaled aerosolized adenovirus type 5-vectored ancestral strain coronavirus disease 2019 (COVID-19) vaccine as a second booster dose approximately 1 year after homologous boosted primary series of inactivated COVID-19 vaccine compared with no second booster. Participants reported nucleic acid or antigen test results weekly until they tested positive or completed predesignated follow-up. After excluding participants infected <14 days after study entry, relative effectiveness among the 6576 participants was 61% in 18- to 59-year-olds and 38% in & GE;60-year-olds and was sustained for 12 weeks. In a real-world study during China's large SARS-CoV-2 BA.5 variant epidemic wave, effectiveness against actively monitored infection of an inhaled adenovirus type 5-vectored COVID-19 vaccine was 61% in 18- to 59-year-olds and 38% in & GE;60-year-olds and was sustained for 12 weeks.

Automated summary

A prospective, observational cohort study in China estimated the short-term effectiveness of an inhaled adenovirus type 5-vectored COVID-19 vaccine as a second booster dose against Omicron BA.5 infection. The vaccine showed a relative effectiveness of 61% in 18-59 year-olds and 38% in ≥60 year-olds, sustained for 12 weeks. The study's findings were based on real-world data during China's SARS-CoV-2 BA.5 variant epidemic wave.