Binding antibodies against respiratory syncytial virus and association with age-specific neutralizing antibodies and hospitalization patterns in Israel

Respiratory Syncytial Virus (RSV) imposes a substantial health burden, particularly in infants and older adults, but comprehensive population-level data describing age-specific antibody responses alongside hospitalization patterns are scarce. To assess RSV seropositivity across demographic and geographic variables, to evaluate age-specific binding and neutralizing antibody responses, and to describe the age distribution of RSV-positive hospitalizations in an independent hospitalized cohort; any comparisons between the serosurvey and the hospitalized cohort are descriptive and hypothesis‑generating. A cross-sectional sero-survey of 1,396 sera samples was conducted to measure RSV binding antibodies using ELISA (values were defined as high-positive, borderline or low-positive). Of them, neutralizing antibodies were assessed in 243 age-stratified sera. An independent cohort of 1,232 RSV-positive hospitalized patients collected during the 2022–2025 winter seasons at a single center was used to evaluate age-specific hospitalization distributions; the two datasets were not linked at the individual level. Overall, the RSV high-seropositivity rate was 7.8%, with infants aged 0–12 months showing the lowest seroprevalence (0.0%) while children aged 13–59 months (15.4%) and adults aged ≥ 60 years (12.9%) showed the highest. RSV geometric mean titers (GMTs) differed significantly by age, increasing from infancy to adulthood and peaking in those aged ≥ 60 years ( p < 0.0001). Higher GMTs were observed among individuals born outside Israel and varied significantly by district, with the highest levels in the South and lowest in Tel Aviv. Among the hospitalized cohort, infants accounted for the largest proportion of RSV-positive hospitalizations (35.3%), followed by adults aged ≥ 60 years (25.4%). These age‑specific patterns are reported for independent datasets and any juxtaposition is descriptive. Neutralizing antibody analysis in 243 age-stratified sera demonstrated strong correlations between binding and neutralizing antibodies in infants and young children, but weak to moderate correlations in older age groups. Age-specific differences in both the quantity and functional quality of antibodies were observed, with marked demographic variation. Because the serosurvey and hospitalized cohort are independent, the observed concordance or discordance between antibody patterns and hospitalization distribution is descriptive and does not establish causality. Whether these patterns relate to RSV susceptibility or hospitalization risk warrants further investigation in prospective studies with individual-level data. These findings highlight the need for targeted vaccination and prevention strategies, particularly for high-risk groups such as infants and older adults.