Epidemiology of Medically Attended Respiratory Syncytial Virus Lower Respiratory Tract Infection in Japanese Children, 2011–2017.

Background The objective was to report critical respiratory syncytial virus (RSV)–related epidemiological and healthcare resource utilization measures among Japanese children stratified by gestational and chronological age groups. Methods The JMDC (formerly the Japan Medical Data Center) was used to retrospectively identify infants with or without RSV infection (beginning between 1 February 2011 and 31 January 2016, with follow-up through 31 December 2017). The incidence of RSV medically attended lower respiratory tract infection (MALRI) was captured by flagging hospitalizations, outpatient, and emergency department/urgent care visits with an RSV diagnosis code during the season. Results Of 113 529 infants and children identified, 17 022 (15%) had an RSV MALRI (14 590 during the season). The RSV MALRI and hospitalization rates in the first 5 months were 14.3/100 child-years (CY) and 6.0/100 CY, respectively (13.4/100 and 5.8/100 CY for full-term infants and 20/100 and 6.8/100 CY for late preterm infants, respectively). Among those with ≥1 type of MALRI event during the RSV season, >80% of children had it by 24 months of chronological age, although this observation differed by prematurity status. Sixty percent of healthcare resource utilization measures started in the outpatient setting. Conclusions This study emphasizes the RSV burden in young children and critically highlights the data needed to make decisions about new preventive strategies. [ABSTRACT FROM AUTHOR]