High Respiratory Syncytial Virus Burden in Children Under 3 Years of Age Across All Care Levels in England

Abstract Recent evidence has shown a substantial RSV burden in healthy term-born children, but there is less data quantifying the relative burden compared to those with co-morbidity or prematurity. There is also limited primary care and emergency department (ED) data due to the lack of routine pathogen detection. These data are important for the development of RSV immunisation strategies. A prospective surveillance study of children < 3 years old, presenting with lower respiratory infection and a sub-study in primary care of upper respiratory infection was conducted. The primary endpoint was RSV prevalence by healthcare setting. Secondary endpoints included proportion of hospitalisations, level of ventilatory support and admission to higher levels of care. An economic analysis assessing the costs associated with healthcare utilisation was also conducted. The primary analysis revealed RSV prevalence was 50.4% in children admitted to hospital, 36.3% in ED discharges, 36.5% in primary care and 12.8% in primary care children with upper respiratory infection. Healthy term-born children accounted for 73.3% of medically-attended RSV cases and 70.1% of hospitalisations. Risk factors for severe disease included any level of prematurity, age < 3 months and congenital cardiac disease. RSV positive cases incurred a higher mean cost than RSV negative cases (mean = £1,706; incremental = £683) per illness. The findings revealed a substantial burden associated with RSV. Even moderate prematurity was a risk factor for severe disease, and these children may not benefit from the full maternal immune response to vaccination and would not be eligible for Nirsevimab under UK guidance, we therefore recommend broadening eligibility to include these children. What is already known on this topic Recent cohort studies have revealed a substantial healthcare and economic RSV burden from previously healthy term-born children which has supported the implementation of a maternal RSV vaccination programme in the UK, providing protection for infants from birth up to 6 months old. What this study adds We have shown that children born prematurely, including moderately preterm children, are at increased risk of severe RSV disease. These children may not benefit from full protection by maternal RSV vaccination, and may not be eligible for Nirsevimab, the long-acting monoclonal antibody, which is currently reserved for only the most high-risk children in the UK. How this study might affect research, practice or policy This data supports broadening eligibility for Nirsevimab, to include preterm children, who were born before full maternal protection from RSV vaccination may have developed, and to infants born to mothers not receiving maternal vaccination.