Burden of RSV in Young Children in High-Income Countries: Incidence Estimates From a Multilevel Meta-Analysis in Primary and Emergency Care

Background: Most respiratory syncytial virus (RSV) infections in children are managed in primary care settings, including ambulatory care and emergency departments (EDs). This study provides adjusted pooled RSV incidence estimates for children under 5 years in primary care settings in high-income countries (HICs). Methods: We used population-based RSV incidence rates from 27 studies collected in a previous systematic review as input parameters. To adjust for heterogeneity in study design, we assessed the impact of four key factors: 1) age, 2) primary care setting (ambulatory care or EDs), 3) data collection period (year-round or seasonal), and 4) study methodology (cohort studies with laboratory-confirmed RSV, healthcare databases, surveillance data). In the final model, we corrected for age, primary care setting, and study methodology. Adjusted pooled RSV incidence estimates were calculated using a multilevel logit-logistic regression model. Results: For children < 5 years, the adjusted pooled RSV incidence estimate in primary care settings was 62.8 per 1000 population (95% CI 45.3–86.6). Incidence was higher in ambulatory care (108.1 per 1000; 95% CI 78.0–148.0) compared to EDs (35.8 per 1000; 95% CI 25.3–50.3). Age-stratified incidence estimates declined with increasing age, showing 86.5 (95% CI 61.6–120.2), 80.3 (95% CI 57.1–111.8), 60.7 (95% CI 43.2–84.6), and 36.5 (95% CI 25.4–52.2) per 1000 for children aged < 6 months, 0–1 year, 0–2 years, and 0–5 years, respectively. Conclusions: This is the first multilevel meta-analysis estimating the RSV-related burden in primary care settings, including both ambulatory and emergency care. These results can be used by decision makers for the introduction of RSV immunization programs.