Effectiveness of inactivated SARS-CoV-2 vaccines against the Delta variant infection in Guangzhou: a test-negative case–control real-world study. Issue 1 (1st January 2021)

• Record Type: Journal Article
• Authors: Li, Xiao-Ning; Huang, Yong; Wang, Wen; Jing, Qin-Long; Zhang, Chun-Huan; Qin, Peng-Zhe; Guan, Wei-Jie; Gan, Lin; Li, Yi-Lan; Liu, Wen-Hui; Dong, Hang; Miao, Yu-Tian; Fan, Shu-Jun; Zhang, Zhou-Bin; Zhang, Ding-Mei; Zhong, Nan-Shan
• Is Part Of: Emerging microbes & infections. Volume 10:Issue 1(2021)
• Page Start: 1751
• Page End: 1759
• Publication Date: 2021-01-01
• Subjects: Coronavirus disease 2019 -- SARS-CoV-2 -- efficacy of vaccination -- Delta variant -- vaccine; Medical microbiology -- Periodicals; Communicable diseases -- Periodicals; Infection -- Periodicals; 616.9041
• DOI: 10.1080/22221751.2021.1969291
• Languages: English
• ISSNs: 2222-1751

Abstract

ABSTRACT: The effectiveness of inactivated SARS-CoV-2 vaccines against the Delta variant, which has been associated with greater transmissibility and virulence, remains unclear. We conducted a test-negative case–control study to explore the vaccine effectiveness (VE) in real-world settings. We recruited participants aged 18–59 years who consisted of SARS-CoV-2 test-positive cases ( n = 74) and test-negative controls ( n = 292) during the outbreak of the Delta variant in May 2021 in Guangzhou city, China. Vaccination status was compared to estimate The VE of SARS-CoV-2 inactivated vaccines. A single dose of inactivated SARS-CoV-2 vaccine yielded the VE of only 13.8%. After adjusting for age and sex, the overall VE for two-dose vaccination was 59.0% (95% confidence interval: 16.0% to 81.6%) against coronavirus disease 2019 (COVID-19) and 70.2% (95% confidence interval: 29.6–89.3%) against moderate COVID-19 and 100% against severe COVID-19 which might be overestimated due to the small sample size. The VE of two-dose vaccination against COVID-19 reached 72.5% among participants aged 40–59 years, and was higher in females than in males against COVID-19 and moderate diseases. While single dose vaccination was not sufficiently protective, the two-dose dosing scheme of the inactivated vaccines was effective against the Delta variant infection in real-world settings, with the estimated efficacy exceeding the World Health Organization minimal threshold of 50%.