A narrative review of COVID-19 epidemiology and mRNA vaccine impact in children < 12 years during the omicron era (November 2021 – December 2025)

INTRODUCTION: COVID-19 continues to pose a burden in children under 12 years of age during the Omicron era (November 2021 - December 2025). Following Omicron's emergence, SARS-CoV-2 seroprevalence increased rapidly, with most children infected by ages 2-4 years. Pediatric hospitalization rates declined after the initial Omicron wave but remained elevated in children under 2 years and in those with underlying conditions. While healthy children typically experience mild illnesses, severe outcomes - including hospitalization, admission to intensive care unit, death, and multisystem inflammatory syndrome - can occur, particularly in unvaccinated children. AREAS COVERED: This narrative review summarizes current evidence on pediatric COVID-19 epidemiology and vaccine impact, including infection rates, severe outcomes, post-acute COVID-19 syndrome (Long COVID), and mRNA vaccine effectiveness and uptake in high-income regions. A literature search included peer-reviewed publications, surveillance data, and reports from health agencies during the Omicron era. EXPERT OPINION: mRNA vaccines are effective in reducing pediatric COVID-19-related morbidity, but uptake remains low globally. Addressing parental concerns, improving vaccine accessibility, and promoting evidence-based communication are critical to increasing uptake. Given the continued disease burden and the potential for severe outcomes, ensuring access to mRNA COVID-19 vaccines for children at higher risk and for families who wish to vaccinate their children is beneficial.