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Effectiveness of Inactivated COVID-19 Vaccines Against COVID-19 Pneumonia and Severe Illness Caused by the B.1.617.2 (Delta) Variant: Evidence from an Outbreak in Guangdong, China

18 Pages Posted: 5 Aug 2021

See all articles by Min Kang

Min Kang

Guangdong Provincial Center for Disease Control and Prevention

Yao Yi

Guangdong Provincial Center for Disease Control and Prevention

Yan Li

Guangdong Provincial Center for Disease Control and Prevention

Limei Sun

Guangdong Provincial Center for Disease Control and Prevention

Aiping Deng

Guangdong Provincial Center for Disease Control and Prevention

Ting Hu

Guangdong Provincial Center for Disease Control and Prevention

Jiayi Zhang

Guangdong Provincial Center for Disease Control and Prevention

Jun Liu

Guangdong Provincial Center for Disease Control and Prevention

Mingji Cheng

Guangdong Provincial Center for Disease Control and Prevention

Shen Xie

Guangdong Provincial Center for Disease Control and Prevention

Min Luo

Guangdong Provincial Center for Disease Control and Prevention

Jing Jiang

Guangdong Provincial Center for Disease Control and Prevention

Yawen Jiang

Sun Yat-sen University (SYSU) - School of Public Health

Shixing Tang

Southern Medical University - School of Public Health

Jianfeng He

Guangdong Provincial Center for Disease Control and Prevention

More...

Abstract

Background: Real-world evidence (RWE) of a vaccine supplements clinical trial data by providing information in populations differing from clinical trial populations, under different epidemiological situations, on alternative outcomes, or against different pathogen lineages. To date, RWE on inactivated COVID-19 vaccines against the highly transmissible SARS-CoV-2 B.1.617.2 (Delta) variant is limited, leaving an important gap in the evidence base of inactivated COVID-19 vaccines for use by immunization programs. 

Methods: Between May and June 2021, an outbreak of the B.1.617.2 variant was discovered and traced in Guangdong, China. Before this outbreak, Guangdong province had started mass vaccination using inactivated vaccines approved by China’s regulator for use in adults. Using surveillance and vaccination data from the outbreak, we assessed the real-world effectiveness of inactivated vaccines against pneumonia and severe illness caused by the B.1.617.2 variant. We enrolled 10813 subjects who were close contacts of laboratory-confirmed cases, categorizing them as an unvaccinated group, a partially vaccinated (1-dose) group, and a fully vaccinated (2-dose) group. We estimated relative risk (RR) and vaccine effectiveness (VE) of the vaccinated groups in relation to the unvaccinated group. 

Findings: Unadjusted and adjusted VE of full vaccination against pneumonia were 77·7% (95% CI 45·1–90·9) and 69·5% (95% CI 42·8–96·3), respectively. Full vaccination was 100% effective against severe illness. Unadjusted and adjusted VE of partial vaccination against pneumonia were 1·4% (95% CI -79·7–45·9) and 8·4% (95% CI -47·6–64·4). Interpretation Full vaccination with inactivated vaccines is effective against pneumonia, severe, and critical illness caused by the B.1.617.2 variant. Effort should be placed to ensure full vaccination of target populations. 

Funding: National Natural Science Foundation of China and Key-Area Research and Development Program of Guangdong.

Declaration of Interest: None to declare.

Ethical Approval: This study was approved by the institutional ethics committee of the Guangdong Provincial Center for Disease Control and Prevention (GDCDC). Data in the study were collected per administrative requirements of disease control and surveillance, and were anonymized for analysis. Participants were informed about the requirements of disease surveillance and provided oral consents.

Suggested Citation

Kang, Min and Yi, Yao and Li, Yan and Sun, Limei and Deng, Aiping and Hu, Ting and Zhang, Jiayi and Liu, Jun and Cheng, Mingji and Xie, Shen and Luo, Min and Jiang, Jing and Jiang, Yawen and Tang, Shixing and He, Jianfeng, Effectiveness of Inactivated COVID-19 Vaccines Against COVID-19 Pneumonia and Severe Illness Caused by the B.1.617.2 (Delta) Variant: Evidence from an Outbreak in Guangdong, China. Available at SSRN: https://ssrn.com/abstract=3895639 or http://dx.doi.org/10.2139/ssrn.3895639

Min Kang

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Yao Yi

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Yan Li

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Limei Sun

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Aiping Deng

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Ting Hu

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Jiayi Zhang

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Jun Liu

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Mingji Cheng

Guangdong Provincial Center for Disease Control and Prevention ( email )

Guangzhou, Guangdong Province
China

Shen Xie

Guangdong Provincial Center for Disease Control and Prevention ( email )

Guangzhou, Guangdong Province
China

Min Luo

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Jing Jiang

Guangdong Provincial Center for Disease Control and Prevention

Guangzhou, Guangdong Province
China

Yawen Jiang (Contact Author)

Sun Yat-sen University (SYSU) - School of Public Health ( email )

China

Shixing Tang

Southern Medical University - School of Public Health ( email )

Guangzhou, 510515
China

Jianfeng He

Guangdong Provincial Center for Disease Control and Prevention ( email )

No.160, Qunxian Road
Panyu District
Guangzhou, Guangdong Province
China

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