Respiratory syncytial virus positivity among hospital admissions for acute respiratory illness in children younger than 5 years of age in low- and middle-income countries: a systematic review and meta-analysis

To estimate the proportion RSV-positive among children aged < 5 years hospitalized with ARI in low- and middle-income countries (LMIC), where 97% of RSV mortality occurs. We conducted a systematic literature search for studies conducted pre-COVID-19 and published 2010—2022 (PROSPERO registration CRD42022361351). We estimated the RSV percent positivity and 95% confidence interval (CI) using random-effects meta-analyses. We assessed heterogeneity in RSV percent positivity using subgroup analyses and univariable meta-regression models. We assessed the influence of study sample size in sensitivity analyses. Seventy-three studies conducted in 37 LMICs were included. The summary estimate of percent RSV-positive from the meta-analysis of children < 5 years hospitalized with ARI was 26.2% (95% CI: 24.3–28.3%), ranging from 18.9% (16.4–21.6%) among children 6– < 60 months to 41.3% (36.4–46.4%) among children 0– < 6 months. Only five studies included children aged < 2 months, but RSV positivity was high among this group (40.2% [35.8–44.7%]). Percent positivity stratified by WHO region ranged from 23.6% in the Africa and Southeast Asian regions to 37.5% in the European region. RSV positivity was similar across country income groups. Univariable meta-regression models indicated that there was significant heterogeneity in RSV percent positivity across subgroups defined by mid-year of the study period, WHO region, number of study sites, recruitment method, hospital type, and specimen type (p < 0.05). RSV detection was high among children aged < 5 years hospitalized with ARI in LMICs across all WHO regions, especially among infants aged < 6 months, among whom RSV may account for almost up to one-half of all ARI hospital admissions. Recent WHO-recommended RSV immunization for all countries may protect young infants aged < 6 months against severe RSV disease.