Il nirsevimab nella prevenzione della bronchiolite da virus respiratorio sinciziale

Background RSV is the leading cause of hospitalization for respiratory infections in infants, such as bronchiolitis. In the epidemic season 2023-2024, in Valle D’Aosta Region of Italy (VdA) a universal prevention program against RSV was implemented to protect all infants aged less than 6 months with Nirsevimab. Here we present preliminary data as of 15Feb/2023 regarding coverage rate and effectiveness of nirsevimab. Methods Written consent to the administration of Nirsevimab and the processing of health data was obtained from parents. Nirsevimab administration data were extrapolated from electronic health records managed by Health Authority of VdA, while hospitalizations data for RSV bronchiolitis were extrapolated from hospital discharge records of the same VdA. Results Nirsevimab was available for all infants from 20/Dec/2023. Coverage rates were 65% (292/448) for infants born from 1/May/2023 to 18/Dec/2023, and 86% (77/89) for infants born from 20/Dec/2023 to 15/Feb/2024. There have been 29 hospitalizations for RSV bronchiolitis, 18 in infants born after 1/May/2023. In the past epidemic season 2022/2023, on the same date, the number of hospitalizations was 61, of which 47 in children born after 1/May/2022. The prevalence of RSV bronchiolitis hospitalization in infants who did not receive Nirsevimab was 8.3% (14/168), while there were no hospitalizations due to RSV bronchiolitis in infants who received Nirsevimab (0/369), p<0.001 (Fisher’s exact test). Conclusions The high coverage rate and the solid effectiveness results of Nirsevimab in VdA, as already demonstrated in other countries such as US, Spain, France, Luxemburg, may support Italian policy makers in the implementation of RSV prevention program among the entire country in the next year. Further data on safety and effectiveness on full epidemic season will better explain the potential of this prevention programme.