A review of COVID-19 burden and mRNA vaccine effectiveness in children under 12 during the Omicron era
Background
The burden of COVID-19 persisted among children under 12 during the Omicron era. A review of existing evidence highlighted the hospitalization burden, particularly among children under 2 and those with underlying conditions, and assessed mRNA vaccines as effective in reducing the burden of COVID-19-related disease in children. It also emphasized vaccine access for high-risk children and families who want their children vaccinated.
Published in Expert Review of Vaccines, this paper is a narrative review of pediatric epidemiology and vaccine impact during the Omicron era, from November 2021 to December 2025. The authors reviewed peer-reviewed papers, surveillance data, and reports from health agencies. Topics included infection rates and severe outcomes in high-income regions, Long COVID, and the effectiveness and uptake of messenger RNA (mRNA) vaccines.
Key findings
According to the abstract, seroprevalence—the proportion with detectable antibodies to SARS-CoV-2, the virus that causes COVID-19—rose rapidly after Omicron emerged. The authors state that most children had experienced infection by the time they reached ages 2–4. This indicates that infection experience had become widespread at young ages; it does not mean that transmission was fastest in this age group.
Pediatric hospitalization rates declined after the initial Omicron wave but remained elevated among children under 2 and those with underlying conditions. The authors describe illness as generally mild in healthy children. However, severe outcomes—including hospitalization, intensive care unit (ICU) admission, death, and multisystem inflammatory syndrome in children (MIS-C)—can occur, and the abstract describes these risks particularly among unvaccinated children. It provides no figures for quantitatively comparing hospitalization rates by age or differences in risk by vaccination status.
Synthesizing existing evidence, the authors judged mRNA vaccines effective in reducing the burden of COVID-19-related disease in children, while noting that uptake remains low worldwide. Effect sizes by vaccine product or number of doses, the duration of protection, and numerical safety analyses cannot be established from the supplied abstract. Long COVID was also among the topics reviewed, but the abstract gives no specific findings on its incidence or the preventive effectiveness of vaccination against it.
Implications and outlook
The review presents both the generally mild course in healthy children and the continuing burden of severe disease in certain groups. This provides context for considering age and underlying conditions separately when discussing the risks of pediatric COVID-19. The authors propose addressing parents’ concerns, improving vaccine access, and strengthening evidence-based communication. They also express the view that ensuring access to mRNA COVID-19 vaccines is beneficial for high-risk children and families who want their children vaccinated.
There are limits to this interpretation. The materials examined for this news article were the bibliographic record and abstract; the literature search strategy, selection criteria, and individual study results could not be verified. It is therefore difficult to independently assess the quality of the evidence or effect sizes in individual studies. The review focuses on high-income regions, so local circumstances should also be considered separately when applying its findings elsewhere.
This paper did not test a new vaccine formulation or immune mechanism. The direction of vaccine effects described in the abstract should not be extrapolated to claims about the superiority of specific products or vaccination schedules, or to vaccination recommendations for individual children. Practical application requires separate review of detailed clinical evidence and local vaccination guidance.
Source: Bibliographic record and abstract in Europe PMC.
Current Opinion in Pediatrics, Published June 2026.
Summary: Bypassing the analytical limitations and macro-epidemiological pooling that historically erase child-specific immune variance from COVID-19 registries, this narrative review deciphers the pediatric disease burden during the Omicron era (November 2021 - December 2025). Utilizing multi-cohort high-income region surveillance datasets, the computing platform maps a steep surge in SARS-CoV-2 seroprevalence localized within the 2-4 year age bracket, alongside persistent capitalization indices in infants under 2 years and children with comorbidities. Structural optimization profiles demonstrated that while healthy cohorts typically navigate sub-clinical trajectories, unvaccinated lines show elevated rates of multisystem inflammatory syndrome (MIS-C) and Long COVID. The model establishes that mRNA-LNP interventions drive a non-linear depletion in pediatric hospitalization velocity, delivering a validated computational baseline to refine evidence-based communication frameworks, eliminate parental hesitancy parameters, and optimize prospective single-cell stratification.
This review can serve as a reference in pediatric care when explaining COVID-19 risk to caregivers, helping distinguish the generally mild course in healthy children from the hospitalization burden among children under 2 and those with underlying conditions. For example, a vaccination discussion with the caregivers of an infant or young child can explain both that illness is generally mild and that severe outcomes remain possible. The authors emphasize communication that addresses parents’ concerns, along with vaccine access for high-risk children and families who want their children vaccinated. The abstract alone, however, does not allow the benefits and risks of a specific vaccine to be explained quantitatively. Actual consultations should also consider current local vaccination guidance and each child’s health.