Frontiers in Public Health (Dec 2023)

Inactivated vaccine effectiveness against symptomatic COVID-19 in Fujian, China during the Omicron BA.2 outbreak

  • Wenjing Ye,
  • Kangguo Li,
  • Zeyu Zhao,
  • Shenggen Wu,
  • Huimin Qu,
  • Yichao Guo,
  • Buasiyamu Abudunaibi,
  • Wu Chen,
  • Shaojian Cai,
  • Cailin Chen,
  • Jiawei Lin,
  • Zhonghang Xie,
  • Meirong Zhan,
  • Jianming Ou,
  • Yanqin Deng,
  • Tianmu Chen,
  • Kuicheng Zheng

DOI
https://doi.org/10.3389/fpubh.2023.1269194
Journal volume & issue
Vol. 11

Abstract

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ObjectiveMore than 90% of the Chinese population have completed 2 doses of inactivated COVID-19 vaccines in Mainland China. However, after China government abandoned strict control measures, many breakthrough infections appeared, and vaccine effectiveness against Omicron BA.2 infection was uncertain. This study aims to investigate the real-world effectiveness of widely used inactivated vaccines during the wave of Omicron variants.MethodsTest-negative case-control study was conducted in this study to analyze the vaccine effectiveness against symptomatic disease caused by the Omicron variant (BA.2) in Fujian, China. Conditional logistic regression was selected to estimate the vaccine effectiveness.ResultsThe study found the vaccine effectiveness against symptomatic COVID-19 is 32.46% (95% CI, 8.08% to 50.37%) at 2 to 8 weeks, and 27.05% (95% CI, 1.23% to 46.12%) at 12 to 24 weeks after receiving booster doses of the inactivated vaccine. Notably, the 3–17 years group had higher vaccine effectiveness after 2 doses than the 18–64 years and over 65 years groups who received booster doses.ConclusionInactivated vaccines alone may not offer sufficient protection for all age groups before the summer of 2022. To enhance protection, other types of vaccines or bivalent vaccines should be considered.

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