Epidemiology of COVID-19 infection in young children under five years: A systematic review and meta-analysis

Vaccine. 2021 Jan 22;39(4):667-677. doi: 10.1016/j.vaccine.2020.11.078. Epub 2020 Dec 5.


Introduction: Emerging evidence suggests young children are at greater risk of COVID-19 infection than initially predicted. However, a comprehensive understanding of epidemiology of COVID-19 infection in young children under five years, the most at-risk age-group for respiratory infections, remain unclear. We conducted a systematic review and meta-analysis of epidemiological and clinical characteristics of COVID-19 infection in children under five years.

Method: Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses , we searched several electronic databases (Pubmed, EMBASE, Web of Science, and Scopus) with no language restriction for published epidemiological studies and case-reports reporting laboratory-confirmed COVID-19 infection in children under five years until June 4, 2020. We assessed pooled prevalence for key demographics and clinical characteristics using Freeman-Tukey double arcsine random-effects model for studies except case-reports. We evaluated risk of bias separately for case-reports and other studies.

Results: We identified 1,964 articles, of which, 65 articles were eligible for systematic review that represented 1,214 children younger than five years with laboratory-confirmed COVID-19 infection. The pooled estimates showed that 50% young COVID-19 cases were infants (95% CI: 36% - 63%, 27 studies); 53% were male (95% CI: 41% - 65%, 24 studies); 43% were asymptomatic (95% CI: 15% - 73%, 9 studies) and 7% (95% CI: 0% - 30%, 5 studies) had severe disease that required intensive-care-unit admission. Of 139 newborns from COVID-19 infected mothers, five (3.6%) were COVID-19 positive. There was only one death recorded.

Discussion: This systematic review reports the largest number of children younger than five years with COVID-19 infection till date. Our meta-analysis shows nearly half of young COVID-19 cases were asymptomatic and half were infants, highlighting the need for ongoing surveillance to better understand the epidemiology, clinical pattern, and transmission of COVID-19 to develop effective preventive strategies against COVID-19 disease in young paediatric population.

Keywords: COVID-19; COVID-19 newborns; Children younger than five years.

Publication types

  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Adult
  • Asymptomatic Diseases
  • COVID-19 / epidemiology*
  • COVID-19 / pathology
  • COVID-19 / transmission*
  • COVID-19 / virology
  • Child, Preschool
  • Epidemiological Monitoring
  • Female
  • Humans
  • Incidence
  • Infant
  • Infant, Newborn
  • Infectious Disease Transmission, Vertical / statistics & numerical data*
  • Intensive Care Units
  • Male
  • Mothers
  • Publication Bias / statistics & numerical data
  • SARS-CoV-2 / pathogenicity*
  • Severity of Illness Index