Acceptability and Safety of Nirsevimab in Japanese Infants

Acceptability and Safety of Nirsevimab in infants as per routine immunization practice in Japan - SYMPHONIE 2

Status

Recruiting

Phases

Phase 4

Study type

Observational

Source

JPRN

Registry ID

JPRN-jRCT1041240189

Enrollment

8500

Registered

2025-02-14

Start date

2025-02-14

Completion date

Unknown

Last updated

2026-06-29

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Respiratory Syncytial Virus Infection Acute Respiratory Infection, Respiratory Syncytial Virus

Interventions

None listed

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: 1. Neonates and infants with a residential address in Mie Prefecture. 2. Neonates and infants aged 12 months or younger, born between November 1, 2024, and October 31, 2025. 3. Neonates and infants who meet the eligibility criteria for nirsevimab prophylaxis but do not fall under the definition of preventive administration (in such cases, administration would be conducted under insurance reimbursement rather than under this study) a) Neonates and infants aged 12 months or younger born preterm at 28 weeks or less of gestational age. b) Neonates and infants aged 6 months or younger born preterm at 29 - 35 weeks of gestational age. c) Neonates and infants who have received treatment for chronic lung disease within the past 6 months. d) Neonates and infants with congenital heart disease with hemodynamic abnormalities. e) Neonates and infants with immunodeficiency. f) Neonates and infants with Down syndrome. 4. Consent for participation in this study has been obtained from the representatives.

Exclusion criteria

Exclusion criteria: 1. Neonates and infants with a history of hypersensitivity to nirsevimab or its components. 2. Neonates and infants with a confirmed fever (37.5 degrees Celsius or higher). 3. Neonates and infants diagnosed by a physician as having a severe acute illness. 4. Neonates and infants with a history of palivizumab administration during the study period. 5. Neonates and infants for whom administration is deemed inappropriate by a physician.

Design outcomes

Primary

Measure	Time frame
Acceptability of Nirsevimab	—

Secondary

Measure	Time frame
Adverse Events After Nirsevimab Administration Willingness to Receive Nirsevimab and the Reasons for It	—

Contacts

Public ContactShingo Mitsushima

Mie University Graduate School of Medicine

mitsushima@med.mie-u.ac.jp+81-59-231-5012

Outcome results