Laboratory-confirmed respiratory syncytial virus (RSV) hospitalizations: a national all ages cross-section evaluation, 2020-2024.

Background: New vaccines and monoclonal antibody (mAb) against respiratory syncytial virus (RSV) were recently approved for adults and infants, respectively. However, their inclusion in national vaccination programs has been slow. Accurate assessment of RSV disease burden among all ages is essential for the global introduction of these agents.

Methods: We evaluated all-ages burden of RSV hospitalizations, from 2020 to 2024, based on data collected by a new national laboratory-based hospital surveillance system. RSV-positive respiratory samples from patients hospitalized in general hospitals nationwide were reported. Data were analyzed by RSV circulation periods and age-group to determine hospitalization rates and 30-day mortality (30-DM) rates. We compared the laboratory-confirmed hospitalization rates with rates previously calculated based on ICD-9 codes.

Results: RSV-confirmed hospitalizations were reported for all age-groups. The highest RSV hospitalization rates were found among patients < 1 year old. Patients ≥ 60 years old had the highest RSV hospitalization rates among ≥ 5 years old patients, and their 30-DM rates reached 14.7%, exceeding those of influenza. During the COVID-19 pandemic, lower rates of RSV-confirmed hospitalizations were reported among ≥ 60 years old patients, probably due to higher adherence to social distancing measures. We found higher numbers and rates of laboratory-confirmed hospitalizations among all age-groups ≥ 1 year old, than those previously reported by our group, based on ICD-9 codes.

Conclusions: Laboratory-confirmation of RSV is paramount for optimal assessment of RSV hospitalization burden, particularly beyond infancy, and for the global adoption of newly developed vaccines and mAb.