tetano
Editor, Senior Moderator
Emerg Microbes Infect
. 2021 Aug 14;1-32.
doi: 10.1080/22221751.2021.1969291. Online ahead of print.
Efficacy of inactivated SARS-CoV-2 vaccines against the Delta variant infection in Guangzhou: A test-negative case-control real-world study
Xiao-Ning Li[SUP] 1 [/SUP], Yong Huang[SUP] 1 [/SUP], Wen Wang[SUP] 1 [/SUP], Qin-Long Jing[SUP] 1 [/SUP], Chun-Huan Zhang[SUP] 1 [/SUP], Peng-Zhe Qin[SUP] 1 [/SUP], Wei-Jie Guan[SUP] 2 [/SUP], Lin Gan[SUP] 3 [/SUP], Yi-Lan Li[SUP] 1 [/SUP], Wen-Hui Liu[SUP] 1 [/SUP], Hang Dong[SUP] 1 [/SUP], Yu-Tian Miao[SUP] 1 [/SUP], Shu-Jun Fan[SUP] 1 [/SUP], Zhou-Bin Zhang[SUP] 1 [/SUP], Ding-Mei Zhang[SUP] 3 [/SUP], Nan-Shan Zhong[SUP] 2 [/SUP]
Affiliations
Abstract
The efficacy 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 efficacy (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% to 89.3%) against moderate COVID-19 and 100% against severe COVID-19 which might overestimate 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%.
Keywords: Coronavirus disease 2019; Delta variant; Efficacy of vaccination; SARS-CoV-2; vaccine.
. 2021 Aug 14;1-32.
doi: 10.1080/22221751.2021.1969291. Online ahead of print.
Efficacy of inactivated SARS-CoV-2 vaccines against the Delta variant infection in Guangzhou: A test-negative case-control real-world study
Xiao-Ning Li[SUP] 1 [/SUP], Yong Huang[SUP] 1 [/SUP], Wen Wang[SUP] 1 [/SUP], Qin-Long Jing[SUP] 1 [/SUP], Chun-Huan Zhang[SUP] 1 [/SUP], Peng-Zhe Qin[SUP] 1 [/SUP], Wei-Jie Guan[SUP] 2 [/SUP], Lin Gan[SUP] 3 [/SUP], Yi-Lan Li[SUP] 1 [/SUP], Wen-Hui Liu[SUP] 1 [/SUP], Hang Dong[SUP] 1 [/SUP], Yu-Tian Miao[SUP] 1 [/SUP], Shu-Jun Fan[SUP] 1 [/SUP], Zhou-Bin Zhang[SUP] 1 [/SUP], Ding-Mei Zhang[SUP] 3 [/SUP], Nan-Shan Zhong[SUP] 2 [/SUP]
Affiliations
- PMID: 34396940
- DOI: 10.1080/22221751.2021.1969291
Abstract
The efficacy 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 efficacy (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% to 89.3%) against moderate COVID-19 and 100% against severe COVID-19 which might overestimate 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%.
Keywords: Coronavirus disease 2019; Delta variant; Efficacy of vaccination; SARS-CoV-2; vaccine.