Effectiveness of Inactivated COVID-19 Vaccines Against Illness Caused by the B.1.617.2 (Delta) Variant During an Outbreak in Guangdong, China

Autor: Min Kang, Yao Yi, Yan Li, Limei Sun, Aiping Deng, Ting Hu, Jiayi Zhang, Jun Liu, Mingji Cheng, Shen Xie, Min Luo, Jing Jiang, Yawen Jiang, Shixing Tang, Jianfeng He
Rok vydání: 2022
Předmět:
Zdroj: Annals of Internal Medicine
ISSN: 1539-3704
0003-4819
DOI: 10.7326/m21-3509
Popis: Real-world evidence on inactivated COVID-19 vaccines against the SARS-CoV-2 B.1.617.2 (Delta) variant is limited. The authors of this cohort study analyzed vaccination, surveillance, screening, tracing, and quarantine data to determine the effectiveness of inactivated COVID-19 vaccines against infections, pneumonia, and severe or critical illness caused by the Delta variant.
Visual Abstract. Effectiveness of Inactivated COVID-19 Vaccines Against the Delta Variant. Real-world evidence on inactivated COVID-19 vaccines against the SARS-CoV-2 B.1.617.2 (Delta) variant is limited. The authors of this cohort study analyzed vaccination, surveillance, screening, tracing, and quarantine data to determine the effectiveness of inactivated COVID-19 vaccines against infections, pneumonia, and severe or critical illness caused by the Delta variant. Visual Abstract. Effectiveness of Inactivated COVID-19 Vaccines Against the Delta Variant. Real-world evidence on inactivated COVID-19 vaccines against the SARS-CoV-2 B.1.617.2 (Delta) variant is limited. The authors of this cohort study analyzed vaccination, surveillance, screening, tracing, and quarantine data to determine the effectiveness of inactivated COVID-19 vaccines against infections, pneumonia, and severe or critical illness caused by the Delta variant.
Background: Real-world evidence on inactivated COVID-19 vaccines against the highly transmissible B.1.617.2 (Delta) variant of SARS-CoV-2 is limited, leaving an important gap in the evidence base about inactivated COVID-19 vaccines for use by immunization programs. Objective: To estimate inactivated vaccine effectiveness (VE) against the B.1.617.2 variant. Design: Retrospective cohort study. Setting: The study was based on the first outbreak of the B.1.617.2 variant in mainland China that was discovered and traced in Guangdong in May and June 2021. Participants: 10 805 adult case patients with laboratory-confirmed infection and close contacts. Measurements: Participants were categorized as unvaccinated, partially vaccinated (1 dose), and fully vaccinated (2 doses). We estimated VE against the primary outcome of pneumonia and the secondary outcomes of infections, symptomatic infections, and severe or critical illness associated with the B.1.617.2 variant. Results: Results are reported in the order of outcome severity. Of 10 805 participants, 1.3% contracted infections, 1.2% developed symptomatic infections, 1.1% had pneumonia, and 0.2% had severe or critical illness. The adjusted VEs of full vaccination were 51.8% (95% CI, 20.3% to 83.2%) against infection, 60.4% (CI, 31.8% to 88.9%) against symptomatic infection, and 78.4% (CI, 56.9% to 99.9%) against pneumonia. Also, full vaccination was 100% (CI, 98.4% to 100.0%) effective against severe or critical illness. By contrast, the adjusted VEs of partial vaccination against infection, symptomatic infection, and pneumonia were 10.7% (CI, −41.2% to 62.6%), 6.8% (CI, −47.4% to 61.0%), and 11.6% (CI, −42.6% to 65.8%), respectively. Limitation: Observational study with possible unmeasured confounders; insufficient data to do reliable subgroup analyses by age and vaccine brand. Conclusion: Full vaccination with inactivated vaccines is effective against the B.1.617.2 variant. Effort should be made to ensure full vaccination of target populations. Primary Funding Source: National Natural Science Foundation of China and Key-Area Research and Development Program of Guangdong Province.
Databáze: OpenAIRE
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