The effect of COVID-19 vaccine to the Omicron variant in children and adolescents: a systematic review and meta-analysis

Front Public Health. 2024 Apr 10:12:1338208. doi: 10.3389/fpubh.2024.1338208. eCollection 2024.

Abstract

Background: Omicron (B.1.1.529), a variant of SARS-CoV-2, has emerged as a dominant strain in COVID-19 pandemic. This development has raised concerns about the effectiveness of vaccination to Omicron, particularly in the context of children and adolescents. Our study evaluated the efficacy of different COVID-19 vaccination regimens in children and adolescents during the Omicron epidemic phase.

Methods: We searched PubMed, Cochrane, Web of Science, and Embase electronic databases for studies published through March 2023 on the association between COVID-19 vaccination and vaccine effectiveness (VE) against SARS-CoV-2 infection in children and adolescents at the Omicron variant period. The effectiveness outcomes included mild COVID-19 and severe COVID-19. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was prospectively registered in PROSPERO (CRD42023390481).

Results: A total of 33 studies involving 16,532,536 children were included in the analysis. First, in children and adolescents aged 0-19 years, the overall VE of the COVID-19 vaccine is 45% (95% confidence interval [CI]: 40 to 50%). Subgroup analysis of VE during Omicron epidemic phase for different dosage regimens demonstrated that the VE was 50% (95% CI: 44 to 55%) for the 2-dose vaccination and 61% (95% CI: 45 to 73%) for the booster vaccination. Upon further analysis of different effectiveness outcomes during the 2-dose vaccination showed that the VE was 41% (95% CI: 35 to 47%) against mild COVID-19 and 71% (95% CI: 60 to 79%) against severe COVID-19. In addition, VE exhibited a gradual decrease over time, with the significant decline in the efficacy of Omicron for infection before and after 90 days following the 2-dose vaccination, registering 54% (95% CI: 48 to 59%) and 34% (95% CI: 21 to 56%), respectively.

Conclusion: During the Omicron variant epidemic, the vaccine provided protection against SARS-CoV-2 infection in children and adolescents aged 0-19 years. Two doses of vaccination can provide effective protection severe COVID-19, with booster vaccination additionally enhancing VE.

Keywords: COVID-19 vaccines; Omicron; SARS-CoV-2 variants; adolescent; child.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Systematic Review

MeSH terms

  • Adolescent
  • COVID-19 Vaccines* / administration & dosage
  • COVID-19 Vaccines* / immunology
  • COVID-19* / epidemiology
  • COVID-19* / prevention & control
  • Child
  • Child, Preschool
  • Humans
  • Infant
  • SARS-CoV-2* / immunology
  • Vaccination / statistics & numerical data
  • Vaccine Efficacy* / statistics & numerical data

Substances

  • COVID-19 Vaccines

Supplementary concepts

  • SARS-CoV-2 variants

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This project was funded by 1.3.5 project for disciplines of excellence, West China Hospital, Sichuan University (ZYGD22009).