Table 1.

Data input summary

Parameter	Description	Uncertainty
Demographic data	Population projection in 2020 [13] Under-1 and under-5 mortality, life expectancy [13], and stillbirth rate [14]	Uncertainty was not taken into account
RSV disease burden	Interpolate the age-specific data (per month) and scale it per country • RSV incidence • Hospitalisation • Mortality among hospitalised patients (probability), then multiply adjustment factor 2.2 × 0.9 for overall death in both hospital and community settings	• Uncertainty around age-specific RSV incidence and hospital mortality; for details, refer to Additional file 1 • Uniform distribution is assumed for the overall death adjustment factor 2.2 (1.5–2.9) and influenza adjustment factor 0.9 (0.8–1)
Immunisation coverage	WHO BCG coverage 2016 as a proxy for both strategies	Uncertainty was not taken into account
Efficacy	70% (50–90%) [15]	Only for scenario analysis
Duration of protection	Maternal, 5 months (3–6 months) [15] mAb, 6 months (4–8 months) [12]	Only for scenario analysis
Health care seeking probabilities	WHO reported children with suspected pneumonia taken to an appropriate health provider (%) (range, 13% in Somalia to 92.3% in Ukraine) as proxies for outpatient visits [16]	Uncertainty was not taken into account
Hospital length of stay	Country-specific data, or 5.8 days (95% CI 5.3–6.4) if data were unavailable [17]	Gamma distribution (alpha = 432.52, beta = 0.014)
Treatment cost for outpatient and hospitalisation	Country-specific data, with pneumonia costs as a proxy for outpatients and hospitalisations, or adjusted from the WHO-CHOICE data [18]	Gamma distribution (for details, refer to Additional file 1)
Intervention cost in USD (including delivery cost)	Maternal, $3 for one dose mAb, $6 for one dose	Only for scenario analysis
Health outcome	Duration of illness, 11.2 days (10.1–12.3) [19] DALYs of moderate ALRI, 0.053 (0.032–0.074) [20] DALYs of severe ALRI, 0.21 (0.139–0.298) [20]	Gamma distribution Duration of illness (α = 398.3, β = 0.014) DALYs of moderate ALRI (α = 24.5, β = 0.002) DALYs of severe ALRI (α = 26.8, β = 0.008)
Discounting	3% for both costs and health outcomes	Not applicable