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Effectiveness of Inactivated SARS-CoV-2 Vaccines During a Delta Variant Outbreak in Hunan Province, China: A Retrospective Cohort Study.
- Source :
- Zoonoses (2737-7466); 2022, Vol. 2 Issue 1, p1-10, 10p
- Publication Year :
- 2022
-
Abstract
- Objective: This study was aimed at investigating the effectiveness of inactivated COVID-19 vaccines against the Delta variant. Methods: We performed a retrospective cohort study of close contacts of people with laboratory-confirmed SARS-CoV-2 infections in Hunan province, China, from July to August 2021. Mixed-effect logistic regression was used to estimate vaccine effectiveness (VE), and analyze the effects of the vaccination status of index cases and the exposure risk level on VE estimation. Results: A total of 1,685 close contacts of 126 index cases were included; 835 (49.6%) had received two doses of inactivated vaccines, and the median interval between the 2nd dose and exposure was 48 days (IQR: 41 to 56 days). Full vaccination was defined as two doses at least 14 days before exposure. Adjusted VE estimates for full vaccination were 54.8% (95% CI: 7.7 to 77.9) and 68.4% (95% CI: 8.5 to 89.1) against symptomatic and moderate-tosevere COVID-19, respectively. VE for inactivated vaccines was difficult to observe if index cases had been fully vaccinated. The estimated VE with respect to infection protection was lower among household than non-household contacts. Conclusion: Complete primary immunization of two-dose inactivated COVID-19 vaccines protected against SARS-CoV-2 Delta variant infection. Infection risk was higher among vaccinated household contacts than vaccinated nonhousehold contacts. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 27377466
- Volume :
- 2
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Zoonoses (2737-7466)
- Publication Type :
- Academic Journal
- Accession number :
- 167352808
- Full Text :
- https://doi.org/10.15212/ZOONOSES-2022-0020