Newborn screening dried blood spots enable population-level measurement of RSV immunity.

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of respiratory infection in young children. Although passive immunization strategies are available for infants, the relationship between population immunity and epidemic intensity remains poorly understood. Measuring maternally derived RSV antibodies in newborns could provide a scalable sentinel approach to monitor population immunity.

OBJECTIVE

To demonstrate the feasibility of using residual newborn dried blood spots (NDBS), collected universally, to quantify population-level RSV antibody immunity at birth.

METHODS

We developed a method to quantify RSV antibody levels and function using residual NDBS from the British Columbia Newborn Screening Program. Assay performance and stability were first evaluated using adult dried blood spot (DBS) and serum controls, then applied to two NDBS sets.

RESULTS

In adult DBS, IgG against RSV pre-fusion (pre-F) protein was stable for at least 30 days and ⁓20-fold lower than corresponding sera. In NDBS, pre-F IgG levels remained stable for 140 days at room temperature, correlated with viral neutralization titers (ρ=0.64, p < 0.0001; N = 159), and showed antigen specificity through competitive blocking with soluble post-F protein across multiple RSV antigens (pre-F, post-F, N, Ga, Gb). ⁓42% of samples were below the lower limit of quantification.

CONCLUSIONS

RSV antibody immunity can be quantified from residual NDBS. This scalable approach enables population-level surveillance of RSV immunity and supports large-scale studies of seasonal RSV epidemiology and correlates of protection across regions.