An observational study in Respiratory Syncytial Virus Infections, Severe Acute Respiratory Infection and Bronchiolitis, Viral, sponsored by Bogotá District Health Secretariat. Active, not recruiting at 1 site in Colombia. Open to participants aged 1 Day to 180 Days. Per ClinicalTrials.gov, last updated 2026-08-06.
Sponsored by Bogotá District Health Secretariat · Observational
This study aims to evaluate the real-world effectiveness of two preventive immunization strategies against Respiratory Syncytial Virus (RSV)-associated severe acute respiratory infection in infants less than six months of age in Bogotá, Colombia. The strategies include maternal vaccination with RSVpreF administered between 28 and 36 weeks of gestation and neonatal immunization with nirsevimab for infants born to mothers who did not receive RSVpreF during pregnancy. Using a test-negative case-control design embedded in the city's sentinel surveillance system, infants hospitalized for severe respiratory infection will be systematically tested for RSV. Comparative vaccine effectiveness will be estimated to determine the impact of maternal RSV vaccination and neonatal monoclonal antibody immunization on RSV-associated hospitalizations, intensive care admissions, and mortality. The study will generate real-world evidence to inform local and regional public health decisions and guide the implementation of cost-effective hybrid immunization strategies against RSV in middle-income settings.
Respiratory Syncytial Virus (RSV) is a leading cause of hospitalization, morbidity, and mortality among infants, particularly during the first months of life. In 2026, Bogotá will introduce a hybrid immunization strategy combining maternal vaccination with RSVpreF during weeks 28-36 of pregnancy and neonatal immunization with nirsevimab for infants whose mothers were not vaccinated. Despite evidence from clinical trials, real-world comparative effectiveness data for hybrid RSV immunization strategies in Latin America remain limited.
This observational study will employ a prospective test-negative case-control design using the city's sentinel surveillance network for severe respiratory infection. All eligible infants under six months hospitalized for severe acute respiratory infection will undergo laboratory testing for RSV. Cases will be defined as RSV-positive infants, and controls as RSV-negative infants. Exposure to RSVpreF or nirsevimab will be validated through Bogotá's immunization registry.
Primary outcomes include laboratory-confirmed RSV-associated hospitalization, admission to intensive care, and death within the first six months of life. Multilevel logistic regression models adjusted for relevant confounders will be used to estimate vaccine effectiveness. Findings will provide rigorous real-world evidence to support policy decisions, optimize resource allocation, and guide the expansion of hybrid RSV prevention strategies in Colombia and other middle-income countries.
306 studies on the registry are indexed under Respiratory Syncytial Virus Infections; 50 are open to participants now.
This study's planned enrollment of 1,097 is above the median of 375 across 76 observational studies indexed under Respiratory Syncytial Virus Infections.
Browse Respiratory Syncytial Virus Infections studies →This is the only study on the registry with Bogotá District Health Secretariat as lead sponsor.
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Infants younger than six months residing in Bogotá, Colombia, hospitalized for severe acute respiratory infection in sentinel hospitals and tested for RSV within 48 hours of admission. The population includes infants exposed to maternal RSVpreF vaccination, neonatal nirsevimab, or neither intervention. Extremely preterm infants (≤32 weeks gestation) and those hospitalized for non-respiratory conditions are excluded.
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Exclusion Criteria:
An infant younger than six months of age, resident in Bogotá, hospitalized for severe acute respiratory infection (SARI) and meeting the district operational criteria for SARI, who has a respiratory specimen collected within ≤48 hours of hospital admission (or repeated within 24-48 hours if the first result was negative) that tests positive for Respiratory Syncytial Virus (RSV) by RT-PCR or a validated antigen assay. Only infants born ≥5 weeks after the start of the maternal RSVpreF vaccination campaign are eligible for inclusion.
Biological: RSVpreF vaccine (Abrysvo) and Nirsevimab (Beyfortus) or unexposed
An infant younger than six months of age, resident in Bogotá, hospitalized for severe acute respiratory infection (SARI) and meeting the same operational criteria as cases, who has a respiratory specimen collected within ≤48 hours of admission (or repeated within 24-48 hours if needed) that tests negative for RSV. Controls may test positive for other respiratory viruses or bacteria. Only infants born ≥5 weeks after the start of the maternal RSVpreF vaccination campaign are eligible.
Biological: RSVpreF vaccine (Abrysvo) and Nirsevimab (Beyfortus) or unexposed
Drug page: Abrysvo
Maternal vaccination administered between 28 and 36 weeks of gestation and Single-dose monoclonal antibody administered to newborns whose mothers did not receive effective RSVpreF vaccination or unexposed
Hospitalization for RSV-associated Severe Acute Respiratory Infection
Proportion of infants hospitalized with laboratory-confirmed Respiratory Syncytial Virus (RSV)-associated severe acute respiratory infection, defined as meeting the district operational criteria for SARI and testing positive for RSV by RT-PCR or validated antigen testing within ≤48 hours of hospital admission. The measure compares the likelihood of RSV-related hospitalization among infants exposed to maternal RSVpreF vaccination, neonatal nirsevimab administration, or no RSV-specific immunization.
Time frame: From birth up to 6 months of age (≤180 days of life)
Plan to share: No
Started Jan 2026 (actual). Primary completion is estimated for Dec 2026, 11 months after the start.
Of 31 observational studies under Respiratory Syncytial Virus Infections, half reached primary completion within 25 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 51. This study's planned 11 months is below that.
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This study is active, not recruiting, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
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Respiratory Syncytial Virus Infections →