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Evaluating ABRYSVO Maternal Vaccine Effectiveness Among Infants

NCT ID: NCT07249320

Last Updated: 2025-12-19

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

ACTIVE_NOT_RECRUITING

Total Enrollment

39456 participants

Study Classification

OBSERVATIONAL

Study Start Date

2025-12-01

Study Completion Date

2027-09-30

Brief Summary

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To generate critical evidence to support vaccine policy and implementation, Pfizer will collaborate with Kaiser Permanente Northern California (KPNC) to study the vaccine effectiveness (VE) of ABRYSVO vaccination during pregnancy in a real-world population. The overall research question of this study is: what is the effectiveness of ABRYSVO vaccination during pregnancy against medically-attended (MA) RSV-associated and all-cause infant outcomes in a large, diverse, real-world population? This study will use a retrospective cohort design and will be conducted within an integrated delivery health care organization using electronic medical record (EMR) data collected during routine standard of care clinical encounters. Study outcomes among infants born to ABRYSVO-vaccinated mothers (exposed group) will be compared with those among infants born to ABRYSVO-unvaccinated mothers (comparison group) initially from birth through 6 months of age, with later assessments from birth through 12 months of age and through 24 months of age as the infants reach these age thresholds and their data become available. There are two categories of outcomes of interest in this study: RSV-specific infant outcomes and non-specific all-cause infant outcomes, assessed within several follow-up windows (birth through 6 months of age, birth through 12 months of age, and/or birth through 24 months of age, depending on the outcome).

Identification of RSV-specific outcomes will be based on the first positive laboratory-confirmed PCR test from a respiratory specimen during a healthcare encounter in a KPNC healthcare setting, occurring during the relevant follow-up window. RSV-positive test results will be combined with International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnostic codes to define the RSV-specific outcomes. RSV-specific outcomes will include: PCR-confirmed RSV, PCR-confirmed RSV hospitalization, PCR-confirmed RSV LRTD, and PCR-confirmed RSV LRTD hospitalization.

Non-specific all-cause infant outcomes will include: all-cause LRTD, all-cause LRTD hospitalization, acute otitis media, and new antibiotic prescription (for any diagnosis). Identification of these outcomes will be based on ICD-10-CM diagnostic codes documented in infant EMRs during a healthcare encounter in a KPNC healthcare setting, occurring during the relevant follow-up window.

Detailed Description

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Conditions

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Respiratory Syncytial Virus (RSV)

Keywords

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Lower respiratory tract infections acute respiratory tract infections RSV maternal immunization

Study Design

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Observational Model Type

COHORT

Study Time Perspective

RETROSPECTIVE

Study Groups

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Exposed

Infants whose mother received ABRYSVO vaccine during pregnancy 14 days or more before delivery

ABRYSVO

Intervention Type BIOLOGICAL

Participants will receive Pfizer's ABRYSVO vaccine as part of standard of care. Vaccine is not administered in this study.

Unexposed

Infants born to mothers who did not receive ABRYSVO during pregnancy will be considered unexposed

No interventions assigned to this group

Interventions

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ABRYSVO

Participants will receive Pfizer's ABRYSVO vaccine as part of standard of care. Vaccine is not administered in this study.

Intervention Type BIOLOGICAL

Eligibility Criteria

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Inclusion Criteria

1. Gestational age at delivery ≥32 0/7 weeks of gestation (earliest gestational age eligible for ABRYSVO vaccination) during the study period
2. Maternal age 18 to 50 years at pregnancy onset
3. At least 1 prenatal visit between pregnancy onset and 20 weeks of gestation
4. Continuous KPNC enrollment for a minimum of 30 days prior to pregnancy onset through to the date of delivery, with no more than a 1-month administrative gap in coverage

Exclusion Criteria

2. Live birth
3. Enrolled as member in KPNC by 3 months of age



Participants meeting any of the following criteria will not be included in the study:

1. Received any licensed or investigational RSV vaccine other than ABRYSVO at any time during pregnancy
2. Received ABRYSVO at ≥37 weeks' gestation
3. Received ABRYSVO at \<32 0/7 weeks' gestation
Minimum Eligible Age

0 Years

Maximum Eligible Age

50 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Pfizer

INDUSTRY

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Pfizer CT.gov Call Center

Role: STUDY_DIRECTOR

Pfizer

Locations

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Pfizer

New York, New York, United States

Site Status

Countries

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United States

Related Links

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https://pmiform.com/clinical-trial-info-request?StudyID=C3671048

To obtain contact information for a study center near you, click here.

Other Identifiers

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C3671048

Identifier Type: -

Identifier Source: org_study_id