Pediatric COVID-19 Hospitalization Risk and Vaccination During Omicron

The VENUS study in Japan found that receiving two or more doses of an ancestral monovalent COVID-19 vaccine was associated with a substantially lower incidence of COVID-19–associated hospitalization among children and adolescents during the Omicron-dominant period.

The study reported an adjusted incidence rate ratio for fully vaccinated versus unvaccinated individuals of 0.429 (95% CI: 0.198–0.930), an approximate 57% relative reduction in hospitalization risk.

Investigators in Japan linked municipal vaccination registries with health insurance claims in a retrospective, population-based cohort of individuals aged 6 months to <18 years during the Omicron wave. They compared hospitalization incidence by vaccination status and estimated adjusted IRRs controlling for age group, sex, underlying medical conditions, municipality, and calendar month. This real-world, population-level approach captures observed hospital admissions rather than trial-modeled efficacy, offering pragmatic evidence relevant to health-service planning.

Age-stratified analyses covered three pediatric bands (6 months to <5 years, 5 to <12 years, and 12 to <18 years). The direction of protection was consistent across age groups, with lower crude incidence rates in fully vaccinated strata: 0, 0.9, and 2.8 per 100,000 person-months for the youngest, middle, and adolescent bands, respectively. Event counts were particularly low among vaccinated children with underlying medical conditions, which constrains precision despite suggesting meaningful protection. The 95% CI around the adjusted IRR (0.198–0.930) supports a confident inference of reduced hospitalization risk while acknowledging remaining statistical uncertainty around the point estimate.

These results support programmatic efforts to increase vaccine uptake among eligible pediatric populations and to consider timing doses to maximize protection before anticipated periods of high SARS-CoV-2 transmission.