Relative effectiveness of a heterologous booster dose with adenovirus type 5 vectored COVID-19 vaccine versus three doses of inactivated COVID-19 vaccine in adults during a nationwide outbreak of omicron predominance, in China: a retrospective, individually matched cohort-control study

• Published in: Emerging microbes & infections Vol. 13; no. 1; p. 2332660
• Main Authors: Jia, Siyue, Yin, Zundong, Pan, Hongxing, Wang, Fuzhen, Liu, Xiaoqiang, Wang, Qing, Zhang, Li, Tang, Jihai, Yang, Hao, Du, Jiangbo, Wang, Zhiguo, Jin, Pengfei, Peng, Zhihang, Tang, Rong, Kang, Guodong, Wang, Xuewen, Li, Simin, Wang, Weixiao, Li, Jingxin, Shen, Hongbing, Zhu, Fengcai
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.12.2024; Taylor & Francis Group
• Subjects: Adult; Aged; China - epidemiology; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 vaccine; COVID-19 Vaccines - administration & dosage; COVID-19 Vaccines - immunology; Disease Outbreaks - prevention & control; Effectiveness; Emerging and Re-Emerging Coronaviruses; Female; hazard ratio; heterologous immunization; homologous immunization; Humans; Immunization, Secondary; Male; Middle Aged; Retrospective Studies; SARS-CoV-2 - genetics; SARS-CoV-2 - immunology; Vaccine Efficacy; Vaccines, Inactivated - administration & dosage; Vaccines, Inactivated - immunology; Young Adult; China; hazard ratio; COVID-19 vaccine; Effectiveness; heterologous immunization; homologous immunization
• ISSN: 2222-1751; 2222-1751
• DOI: 10.1080/22221751.2024.2332660

Effectiveness of heterologous booster regimes with ad5 vectored COVID-19 vaccine in a large, diverse population during the national-scale outbreak of SARS-CoV-2 omicron predominance in China has not been reported, yet. We conducted a large-scale cohort-control study in six provinces in China, and did a retrospective survey on the COVID-19 attack risk during this outbreak. Participant aged ≥18 years in five previous trials who were primed with 1 to 3 doses of ICV received heterologous booster with either intramuscular or orally inhaled ad5 vectored COVID-19 vaccine were included in the heterologous-trial cohort. We performed propensity score-matching at a ratio of 1:4 to match participants in the heterologous-trial cohort individually with the community individuals who received three-dose of ICV as a control (ICV-community cohort). From February 4 to April 10, 2023, 41504 (74.5%) of 55710 individuals completed the survey. The median time since the most recent vaccination to the onset of the symptoms of COVID-19 was 303.0 days (IQR 293.0-322.0). The attack rate of COVID-19 in the heterologous-trial cohort was 55.8%, while that in the ICV-community cohort was 64.6%, resulting in a relative effectiveness of 13.7% (95% CI 11.9 to 15.3). In addition, a higher relative effectiveness against COVID-19 associated outpatient visits, and admission to hospital was demonstrated, which was 25.1% (95% CI 18.9 to 30.9), and 48.9% (95% CI 27.0 to 64.2), respectively. The heterologous booster with ad5 vectored COVID-19 vaccine still offered some additional protection in preventing COVID-19 breakthrough infection versus homologous three-dose regimen with ICV, 10 months after vaccination.