Efficacy of a standardized regional palivizumab administration protocol based on epidemic prediction for the following season.

Introduction: Monthly palivizumab prevents severe respiratory syncytial virus infection among high-risk children. Palivizumab is generally initiated early in an epidemic, but the best timing for initiation is unknown. Reducing the number of infected patients prior to palivizumab administration is a public health challenge.

Methods: Kanagawa Prefecture, Japan, has a regionally standardized protocol for the initiation of palivizumab based on epidemic prediction for the following season. We analyzed the efficacy of this prospective intervention during 2019-2022 using a questionnaire completed by regional hospitals.

Results: The survey response rate was 53.8 %. In 2019, 2021, and 2022, RSV epidemics began in July, May, and June; palivizumab was started in July, May, and April, respectively. In 2020, palivizumab was started in June, but there was no epidemic activity. The median number of palivizumab doses was eight per year. The number of hospitalized patients each year was 1381, 169, 1196, and 1028, with 28, 1, 11, and 13 patients having an indication for palivizumab, respectively. Among them, the number of hospitalized patients before or after the first dose of palivizumab was 16, 1, 10, and 4, respectively. Thirteen of 31 patients (41.9 %) infected before or after the first dose needed care in the pediatric intensive care unit and/or nasal high flow therapy; only three of 22 patients (13.6 %) received the second of more doses needed (p < 0.05).

Conclusions: A standardized regional protocol for palivizumab initiation could be effective in reducing the number of hospitalized and severely ill patients for whom palivizumab is indicated.