An Observational Study to Assess Nirsevimab Immunization Rates in Eligible Infants During Their First RSV Season in the Czechia

August 7, 2026 updated by: Sanofi

The primary objective of this study is to determine the nirsevimab immunization rate in eligible infants in their first RSV-season in Czechia.

The study will focus on:

  1. Assessing nirsevimab immunization rates among eligible infants (according to ČVS recommendation) in their first RSV-season in Czechia (i.e. across all geographies)
  2. Assessing nirsevimab immunisation rates among the "catch-up cohort", i.e. all infants born between April and September.
  3. Assessing nirsevimab immunization rate among the "in-season cohort", i.e. all infants born during the RSV season between October and March.

Secondary objectives are:

  1. To analyze reasons of parents to decide for or against immunization of their infant with nirsevimab.
  2. To assess immunization rates for further subgroups, if sufficient sample for subgroup achieved, e.g. by: risk group (defined chronic condition or pre-term birth status)
  3. To assess concordance of a parent survey results based on randomly sampled parent population using Computer-Assisted Self-Interviewing (CASI) for estimating immunization rates in Czechia with coverage calculated based on pharmacy sales data.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Actual)

257

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Czechia
      • Prague, Czechia, 160 00
        • Sanofi s.r.o.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The study will target a sample of 250 parents of infants born between April 2025 and March 2027.

Eligible participants must be at least 18, reside in Czechia at the time of survey completion and speak Czech.

Description

Inclusion Criteria:

  • Be a parent of an infant born between April 2025/26 and March 2026/27, respectively
  • Permanent residence in Czechia at the time of survey completion and speak Czech
  • Be at least 18 years old at the time of survey completion
  • Agree with privacy policy and AE (Adverse Event) reporting requirements before proceeding with the survey
  • Read and agree to the ICF (Informed Consent Form) by ticking a box before proceeding with the survey

Exclusion criteria:

  • N/A

The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Cohort 1
"Catch-up cohort", i.e. all infants born between April and September in Czechia.
Biological: Nirsevimab Respiratory Syncytial Virus monoclonal antibody
This study will not administer any treatment, only observe the treatment as prescribed in real-world clinical practice
Cohort 2
"In-season cohort", i.e. all infants born during the RSV season between October and March in Czechia.
Biological: Nirsevimab Respiratory Syncytial Virus monoclonal antibody
This study will not administer any treatment, only observe the treatment as prescribed in real-world clinical practice

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The proportion of immunised infants among all enrolled infants
Time Frame: June 2026 - July 2026
A descriptive analysis of immunisation status (yes/no) will be performed using summary statistics.
June 2026 - July 2026
Type of immunisation
Time Frame: June 2026 - July 2026
A descriptive analysis of immunisation status (yes/no) will be performed using summary statistics.
June 2026 - July 2026
Location of immunization
Time Frame: June 2026 - July 2026
A descriptive analysis of immunisation status (yes/no) will be performed using summary statistics.
June 2026 - July 2026

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sanofi

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 15, 2026

Primary Completion (Actual)

June 26, 2026

Study Completion (Actual)

June 26, 2026

Study Registration Dates

First Submitted

June 3, 2026

First Submitted That Met QC Criteria

June 3, 2026

First Posted (Actual)

June 9, 2026

Study Record Updates

Last Update Posted (Actual)

August 10, 2026

Last Update Submitted That Met QC Criteria

August 7, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • RSV25849
  • U1111-1342-0595 (Registry Identifier: ICTRP)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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