An observational study in Respiratory Syncytial Virus (RSV), Respiratory Syncytial Virus and Lower Respiratory Tract Disease, sponsored by Pfizer. Active, not recruiting at 1 site in Australia. Open to participants aged 0 Years to 12 Months. Per ClinicalTrials.gov, last updated 2025-11-19.
Sponsored by Pfizer · Observational
This Pfizer-sponsored real-world retrospective non-interventional study will be conducted within a research network comprised of independent hospitals across Australia using data collected during routine standard of care clinical encounters available in health records, supplemented with information from the official national immunisation registry, the Australian Immunisation Register. Additional data from accredited pathology laboratories will be included. There will be no active enrollment of study participants, no direct contact with study participants, and no collection of any primary data outside of the standard of care.
This study will use a test negative design to evaluate real-world vaccine effectiveness of RSVpreF vaccination during pregnancy against RSV-associated outcomes in infants.
This case-control study using a test negative design will include all infants through 12 months of age who were admitted to one of the participating hospitals with symptoms of respiratory infection, met the clinical case definition of acute respiratory illness, and had a respiratory specimen collected within 10 days prior to hospital admission through 3 days after a hospital admission with an RSV test result through standard of care testing.
The primary objective is to estimate vaccine effectiveness (VE) of ABRYSVO during pregnancy against RSV-positive lower respiratory tract disease (LRTD) hospitalisation among infants from birth through 6 months (0 to ≤180 days) of age.
Baseline characteristics of the study population will be described by case/control status and by maternal RSVpreF vaccination status. Standardised mean differences may be used to compare the distributions (absolute differences >0.10 will be considered meaningful). For all VE objectives, we will use a logistic regression model to compare the odds of maternal ABRYSVO vaccination during pregnancy between test-positive cases and test-negative controls, generating an odds ratio (OR) and 95% CI and we will use multivariable logistic regression to compute an adjusted OR (aOR), from which we will derive final VE estimates, adjusted for potential confounding, according to the formula: VE = (1-aOR) x 100%.
617 studies on the registry are indexed under Respiratory Tract Diseases; 111 are open to participants now.
This study's planned enrollment of 1 is below the median of 294 across 216 observational studies indexed under Respiratory Tract Diseases.
Browse Respiratory Tract Diseases studies →Pfizer is the lead sponsor of 3,244 studies on the registry; 139 are open to participants now.
Of its 582 completed or terminated interventional studies of FDA-regulated products, 381 (65%) have results posted.
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This hospital-based retrospective study will be conducted in up to 9 hospitals across 6 states/territories in Australia, supported by the Paediatric Active Enhanced Diseases Surveillance Network.
Given the retrospective nature of this study, hospitals that already function as national sentinel units for respiratory virus surveillance, or have robust clinical, laboratory or epidemiological surveillance will be included. Each participating hospital conducts year-round standard of care testing for acute respiratory illness which includes respiratory virus panel test using PCR.
Study will include all infants through 12 months of age who were admitted to one of the participating hospitals with symptoms of respiratory infection, met the clinical case definition of acute respiratory illness, and had a respiratory specimen collected within 10 days prior to hospital admission through 3 days after a hospital admission with an RSV test result through standard of care testing.
Participants must meet all of the following inclusion criteria to be eligible for inclusion in the study:
Exclusion Criteria:
Participants meeting any of the following criteria will not be included in the study:
Infants who meet the respiratory clinical case definition and test positive for RSV (result obtained from standard of care testing with specimen collected within 10 days prior to hospital admission through 3 days after a hospital admission).
Biological: ABRYSVO
Infants who meet the respiratory clinical case definition and test negative for RSV (result obtained from standard of care testing with specimen collected within 10 days prior to hospital admission through 3 days after a hospital admission).
Biological: ABRYSVO
This is a non-interventional retrospective study; therefore, ABRYSVO vaccine has already been administered according to the standard of care. ABRYSVO is a bivalent RSV prefusion F protein-based vaccine (RSVpreF) composed of two prefusion F proteins to protect against both RSV-A and RSV-B.
Also known as: RSVpreF, RSV Prefusion F
Estimate vaccine effectiveness of ABRYSVO during pregnancy against RSV-positive lower respiratory tract disease hospitalisation among infants.
RSV-positive lower respiratory tract disease hospitalisation occurring 0 to ≤180 days after birth.
Time frame: From birth through 6 months (0 to ≤180 days) of age.
Estimate vaccine effectiveness of ABRYSVO during pregnancy against RSV-positive lower respiratory tract disease hospitalisation among infants.
RSV-positive lower respiratory tract disease hospitalisation occurring 0 to ≤180 days after birth subgrouped by: * gestational age at ABRYSVO vaccination. * gestational age at birth. * time from ABRYSVO vaccination to birth. * time intervals of infant age at illness, including cumulative (e.g., 0 to ≤3 months, 0 to ≤6 months) and discrete (e.g., 0 to ≤3 months, \>3 to ≤6 months) age intervals.
Time frame: From birth through 6 months (0 to ≤180 days) of age within key subgroups.
Estimate vaccine effectiveness of ABRYSVO during pregnancy against RSV-positive severe lower respiratory tract disease hospitalisation among infants.
RSV-positive lower respiratory tract disease hospitalisation occurring 0 to ≤180 days after birth subgrouped by: * gestational age at ABRYSVO vaccination. * gestational age at birth. * time from ABRYSVO vaccination to birth. * time intervals of infant age at illness, including cumulative (e.g., 0 to ≤3 months, 0 to ≤6 months) and discrete (e.g., 0 to ≤3 months, \>3 to ≤6 months) age intervals.
Time frame: From birth through 6 months (0 to ≤180 days) of age and within key subgroups.
Estimate vaccine effectiveness of ABRYSVO during pregnancy against RSV-positive acute respiratory illness hospitalisation among infants.
RSV-positive acute respiratory illness hospitalisation occurring 0 to ≤180 days after birth subgrouped by: * gestational age at ABRYSVO vaccination. * gestational age at birth. * time from ABRYSVO vaccination to birth. * time intervals of infant age at illness, including cumulative (e.g., 0 to ≤3 months, 0 to ≤6 months) and discrete (e.g., 0 to ≤3 months, \>3 to ≤6 months) age intervals.
Time frame: From birth through 6 months (0 to ≤180 days) of age and within key subgroups.
Plan to share: No — Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
No publications or documents are linked to this record.
This study is active, not recruiting, as verified in Nov 2025. You cannot join it, but the record below documents what was studied.
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