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. 2022 Jan;64(1):e14957.
doi: 10.1111/ped.14957. Epub 2021 Dec 17.

Epidemiology of respiratory syncytial virus in Japan: A nationwide claims database analysis

Yasuhiro Kobayashi  1 , Kanae Togo  2 , Yasmeen Agosti  3 , John M McLaughlin  4
Affiliations

Epidemiology of respiratory syncytial virus in Japan: A nationwide claims database analysis

Yasuhiro Kobayashi et al. Pediatr Int. 2022 Jan.

Abstract

Background: Respiratory syncytial virus (RSV) is a major cause of hospitalization for bronchiolitis and pneumonia in infancy. In Japan, limited data are publicly available on RSV epidemiology and clinical characteristics among infants.

Methods: This retrospective study described RSV incidence, seasonality, patient characteristics, resource use, and clinical outcomes among Japanese children <2 years from January 2017 through December 2018. The RSV cases were identified using the Japanese Medical Data Center database.

Results: In the database, 9,711 and 8,509 RSV patients <2 years were identified in 2017 and 2018, respectively. Of these, 25% required hospitalization. Ninety percent of hospitalized patients did not have a known RSV risk factor. Nineteen percent of hospitalized patients experienced dehydration, and 12% had acute respiratory failure. Hospitalization lasted 1 week on average and 7% required some type of mechanical ventilation. The peak of hospitalizations occurred at 2 months. The incidence of RSV hospitalization in children <2 years was 23.2 per 1,000 person-years, which increased to 35.4 per 1,000 for infants <6 months. This age group accounted for 40% of all RSV-associated hospitalizations among children <2 years.

Conclusions: Roughly one-fourth of all RSV patients <2 years were hospitalized. Ninety percent of these did not have an underlying risk condition. This underscores that RSV can cause serious disease among all young children. Three to four out of every 100 Japanese children <6 months were hospitalized for RSV, and this age group accounted for ~40% of all RSV-associated hospitalizations. Novel and broad-based RSV prevention strategies, especially those targeting young infants, are needed.

Keywords: Japan; epidemiology; respiratory syncytial virus.

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Conflict of interest statement

This study was sponsored by Pfizer Japan Inc. All authors are employees of Pfizer Japan Inc. and Pfizer Inc. Dr Togo and Mr Kobayashi report personal fees from Pfizer Japan Inc., stock from Pfizer Inc., during the conduct of the study. Dr McLaughlin and Dr Agosti report personal fees and stock from Pfizer Inc. during the conduct of the study.

Figures

Fig. 1
Fig. 1
Number of RSV patients in the JMDC population by age in months and care setting for 2018 and 2017. JMDC: Japan Medical Data Center; RSV: respiratory syncytial virus; All RSV patients: patients with only outpatient visit or hospitalization; Only Outpatients: patients with only outpatient visit; Inpatients: patients with hospitalization. (formula image): All RSV patients; (■): Inpatients; (□): Outpatients only.
Fig. 2
Fig. 2
Numbers of RSV cases (<2 years) in the JMDC population for 2018 and 2017 by calendar month. JMDC: Japan Medical Data Center; RSV: respiratory syncytial virus; Outpatient Only: patients with only outpatient visit; Inpatient: patients with hospitalization; (■): Inpatients; (□): Outpatients only.
See this image and copyright information in PMC

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