Evaluation of the effectiveness and impact of Nirsevimab in Galicia

The purpose of NIRSE-GAL is to evaluate the impact of the inclusion of nirsevimab in the Galician immunisation schedule on the prevention of Respiratory Syncytial Respiratory Syncytial Virus (RSV) infections in children.

About us

The study NIRSE-GAL is a joint effort between the public health authorities of Galicia (Dirección Xeral de Saude Pública, Xunta de Galicia), particularly with the epidemiology unit and research and academic institutions (Instituto de Investigación Sanitaria de Santi-ago de Compostela), particularly with the Genetic, vaccines, Infectious Diseases and Pediatrics research group (GENVIP).

Both groups agreed in the importance of doing an effectiveness evaluation for the recent inclusion of nirsevimab as part of the Galician immunization program. This collaboration ensures an analysis of effectiveness that includes the perspectives of public health, research, and clinical practice.

of the study

The primary objective of the study is to evaluate the effectiveness of nirsevimab on hospitalization for Respiratory Sincitial Virus (RSV) related to lower respiratory track infections (LRTI) during the RSV season (which starts on October 1st and ends on March 1st) in 3 groups of children: Infants born during RSV season, infants younger than 6 months at the start of RSV season and high-risk children younger than 24 months at the start of RSV season.

Secondary objectives include:
To evaluate nirsevimab coverage.
To estimate the effectiveness of nirsevimab in Reducing the risk of:
  1. Very severe RSV-related LRTI defined by requiring neonatal and/or pediatric ICU admission.
  2. Very severe RSV-related LRTI defined by label of severity.
  3. All cause LRTI hospitalization
  4. All cause hospitalization
To evaluate the impact of nirsevimab on primary care/healthcare consumption.
To assess longitudinally the impact of nirsevimab on (recurrent) wheezing and asthma.
To study the above mentioned primary and secondary endpoints in the 2nd and 3rd year after nirsevimab administration.


Nirsevimab, an extended half-life monoclonal antibody against RSV, was approved in 2022 to prevent LRTI caused by RSV in newborns and infants during their first RSV season. It is a monoclonal antibody to be administered in a single dose and with instantaneous efficacy that does not present any serious adverse reaction, as indicated in the summary of product characteristics. (1)

Galicia, an autonomous community in Northwest Spain, is the first region in the world to introduce nirsevimab as part of the 2023 National Immunization Program (NIP).(2) This NIP structures the immunization campaign with nirsevimab around three immunization groups:

  • I


    Born from September 25, 2023 to March 31, 2024. They will receive a dose after birth.
  • II


    Born between 1 April and 24 September 2023. They will receive a dose at the beginning of the season.
  • III


    Born, with risk factors, between 1 October 2021 and 31 March 2023. See the full list in Table 1.
Tabla 1 : eligible patients for 2023-2024 RSV prophylaxis campaign with nirsevimab in Galicia (Spain).


All infants born during RSV season, i.e. from 25th September 2023 to 31 March 2025, will receive 1 dose of nirsevimab in the hospital, in the first 24 hours of life, unless medically contraindicated.


Immunization of all infants under 6 months at the start of the RSV season will receive 1 dose of nirsevimab in their reference hospitals following a flexible electronic personal citation, within 3 weeks of the start of the RSV prophylaxis campaign.

High risk

Any infant with any of the conditions listed below and under 24 months of age at the start of the RSV campaign, will be cited in the first week of the campaign to receive nirsevimab in their reference hospital.

  • Patients with congenital heart diseases featuring significant hemodynamic impact, whether cyanotic or acyanotic.
  • Patients with other underlying pathologies that pose a high risk for severe bronchiolitis due to RSV
  • Severe immunosuppression:
    • Oncohematological diseases
    • Continuous treatment with immunosuppressants
    • Primary immunodeficiencies, with special attention to:
      • Severe combined immunodeficiency
      • Congenital agammaglobulinemia
  • Congenital metabolic disorders
  • Neuromuscular diseases
  • Severe pulmonary diseases
  • Genetic syndromes with significant respiratory issues
  • Trisomy 21
  • Cystic fibrosis
  • Bronchopulmonary dysplasia
  • Premature infants under 35 weeks (including those with a gestational age under 29 weeks), a single dose before reaching 12 months of age

To evaluate the effectiveness of nirsevimab on hospitalization for RSV-related LRTI we have designed a longitudinal observational study based on routinely collected data on hospital and health care use for RSV infections. This is possible because Galicia has a fully digitalized public health system where hospitalizations, primary care, medical prescriptions and dispensations, and vaccination, among others, are automatically registered, allowing for data extraction in a real time manner.

The Galician public health registries will be used for data collection including baseline information and follow-up data. Historical data will be retrieved for comparison purposes. Active monitoring of RSV cases will start as of September 2023. The study aims to observe and analyze data from all the eligible children in Galicia which is expected to be approximately 14,000 starting in October 2023 with 3 years follow up period (end period: October 2026).


Results are presented as reports in a weekly basis. Each report includes summaries of immunization coverage for each of the immunization’s groups, evolution of the RSV epidemic wave, and RSV hospitalization. 

The RSV hospitalization summary includes figures and tables for weekly RSV hospitalization rates and cumulative rates comparing 2023-24 epidemic weeks with previous seasons for 3 cohorts:

Births between April and September

For current season 2023-24, it includes catch-up (children born between April 1 and September 24, 2023); for the comparison with previous seasons, data was collected from children born between April 1 and September 30 of the start of season year.

Infants under 2 months of age

For the current season, this group is dynamic and will begin with a high proportion of catch-up children; as weeks go by, the percentage of infants immunized at birth will increase, until reaching 100% on 25 November.

Infants under 6 months of age

Also for this group, at the beginning of the wave the majority of infants come from the catch-up group.

Conferences and congresses

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RSVVW '24 (Resvinet)
A Global Conference on Novel RSV Preventive and Therapeutic Interventions.
Information and attached files
ESPID 2024
Information and attached files
Information and attached files
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