Recommendations for COVID-19 vaccination of children aged 6 months to 4 years

SARS-CoV-2 infectionin those aged 6months to 4 yearsis often asymptomatic or mild. However,althoughepidemiological evidence showsthat whilerisk ofhospitalisation andsevere diseasein this age group is very low, it is higher than inolder children.

• Since the beginning of the pandemic over 3,500 children were hospitalisedwithCOVID-19in Ireland. Of that number, 1,075 were aged 6 months to4 years; theyaccounted for over a third of paediatric ICU (PICU)admissions, 72% (18/25) of which occurred during the Omicron wave.
• Since 1 September 2022there has been a downward trend in COVID-19 cases, hospitalisations and ICU admissionsin all age groups. Of those aged 6 months to 4 years,90 were hospitalised,less than five required ICU admission and there wereno deaths.
• In the US,there was a significant increase in paediatric cases of COVID-19 and associated hospitalisations in 2022, mostly due to Omicron. Of paediatric COVID-19hospitalisations, 86% weredue toCOVID-19.Therate of hospitalisationand severedisease washighestinthoseaged 6months to 4 yearscompared to older children and adolescents.
• Although the risk of hospitalisation is higher in thosewith underlying conditions, internationally 50-97% of hospitalised children in this age group had noknown risk factorfor severedisease.In Ireland,53% of COVID-19 PICUadmissions had no underlying condition.
• Multisystem Inflammatory Syndrome in Children (MIS-C) is a rare complication after symptomatic or asymptomatic SARS-CoV-2 infection thataffectschildren as young as threemonths of age. COVID-19 vaccination has been shown to reduce the risk of MIS-Cin older children and adolescentsand similar benefit is expectedin this age group.
• On 19 October 2022 the European Medicines Agency (EMA)approved formulations ofComirnaty and Spikevax mRNA vaccines for use in those aged 6 months to4 yearsand 5 years respectively.Paediatric formulationsof Spikevax arenot available in Ireland.
• In clinical trials the immune response of children aged 6 months to 4 yearsto the recommended lower dosesof thevaccines was comparable to thatin adolescents and young adultswho received higher doses.
• Post-marketing evidence shows that mRNA vaccines in older age groups arehighlyeffective at preventing COVID-19 related hospitalisation, severe illnessand death.•High SARS-CoV-2seroprevalence rateshave beenreported in all children in the UK,Swedenand Finland.Of 171children aged0-4yearsattending Irish hospitals,SARS-CoV-2seroprevalence was 73% and thus they areexpected to have someimmunity.
• Evidencein older age groups shows thatvaccination of those previously infected confersadditional protection.
• Vaccine benefit is most evident for children with underlying conditions for whom the risk of severe COVID-19 is greatest.
• In the context of the current epidemiology, high seroprevalence and declining infection rates, the benefits of COVID-19vaccinationfor the healthy child are more nuancedand are influenced by historyand timing of previous infection aswell as the need to minimise risks of COVID-19 within a household.