The contribution of child, family and health service factors to respiratory syncytial virus (RSV) hospital admissions in the first 3 years of life: birth cohort study in Scotland, 2009 to 2015

Introduction: Several vaccines for respiratory syncytial virus (RSV) are under development. Designing an effective vaccination programme for RSV requires information about the relative contribution of risk factors for severe RSV symptoms. / Aim: To inform preventive strategies in Europe by quantifying the contribution of key child, family and health service risk factors to the burden of RSV hospital admissions in young children. / Methods: We constructed a birth cohort study of all singleton children born in Scotland between October 2009 and September 2012 using linkage between birth registration, maternity, vaccination and hospital admission records, with follow-up until the age of 3 years. RSV-confirmed hospital admissions were defined using linkage to national laboratory surveillance data. We estimated hospital admission rates per 1,000 child years and length of stay according to each risk factor. Cox proportional hazard regression models were used to estimate adjusted hazard ratios. / Results: There were 5,185 RSV admissions among the 169,726 children in the cohort: 48.6% of admissions occurred before the age of 6 months, and 29.6% after the age of 1 year. Children born prematurely, small for gestational age, between July and December, with chronic conditions, older siblings, mothers < 30 years old or delayed infant vaccination had a significantly increased risk of admission. Minimising the risk posed by older siblings could reduce RSV admissions by up to 34%. / Conclusion: Future RSV vaccination programmes must protect children throughout early childhood. Vaccination and/or interventions to reduce transmission by older siblings could substantially reduce RSV hospital admissions

Risk factors for admission to hospital with laboratory-confirmed influenza in young children: birth cohort study

We determined risk factors for influenza hospital admission in children aged <2 years to guide the design of paediatric vaccination programmes. We linked all singleton live births in Scotland from 2007 to 2015 to hospital administrative data and influenza laboratory reports. Cox proportional hazard models were used to identify birth and family risk factors for influenza admissions. There were 1115 influenza admissions among 424 048 children. 85.1% of admitted children were born at term and were not in a high-risk group. Presence of an older sibling was strongly associated with increased risk of influenza admission, particularly for children aged <6 months: hazard ratio for second- versus first-born child was 2.02 (95% CI 1.52–2.69). Maternal age <30 years and birth during autumn (age <6 months) or spring (age 6–23 months) were also associated with admission risk. Targeting vaccination programmes to high-risk children will not prevent the vast majority of influenza admissions. Parents of children aged <2 years should be advised that vaccination of older siblings will protect younger children against influenza infection. As evidence of the impact of the universal influenza vaccine programme emerges, there may be a need to reconsider universal influenza vaccination in children aged 6 months to 2 years in the UK