SARS-CoV-2 seroprevalence in children worldwide: a systematic review and meta-analysis

The higher hospitalisation rates of those aged 0–19 years (referred to herein as ‘children’) observed since the emergence of the immune-evasive SARS-CoV-2 Omicron variant and subvariants, along with the persisting vaccination disparities highlighted a need for in-depth knowledge of SARS-CoV-2 sero-epidemiology in children. Here, we conducted this systematic review to assess SARS-CoV-2 seroprevalence and determinants in children worldwide. In this systematic review and meta-analysis study, we searched international and preprinted scientific databases from December 1, 2019 to July 10, 2022. Pooled seroprevalences were estimated according to World Health Organization (WHO) regions (at 95% confidence intervals, CIs) using random-effects meta-analyses. Associations with SARS-CoV-2 seroprevalence and sources of heterogeneity were investigated using sub-group and meta-regression analyses. The protocol used in this study has been registered in PROSPERO (CRD42022350833). We included 247 studies involving 757,075 children from 70 countries. Seroprevalence estimates varied from 7.3% (5.8–9.1%) in the first wave of the COVID-19 pandemic to 37.6% (18.1–59.4%) in the fifth wave and 56.6% (52.8–60.5%) in the sixth wave. The highest seroprevalences in different pandemic waves were estimated for South-East Asia (17.9–81.8%) and African (17.2–66.1%) regions; while the lowest seroprevalence was estimated for the Western Pacific region (0.01–1.01%). Seroprevalence estimates were higher in children at older ages, in those living in underprivileged countries or regions, and in those of minority ethnic backgrounds. Our findings indicate that, by the end of 2021 and before the Omicron wave, around 50–70% of children globally were still susceptible to SARS-CoV-2 infection, clearly emphasising the need for more effective vaccines and better vaccination coverage among children and adolescents, particularly in developing countries and minority ethnic groups. None.