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Impact and Effectiveness of ABRYSVO® Vaccination During Pregnancy

Active Not RecruitingN/A

Sponsor: Pfizer

Conditions: Respiratory Syncytial Virus, Respiratory Tract Diseases

Interventions: ABRYSVO

Countries: Argentina

This study will be conducted in collaboration with a research network of independent hospital sites to evaluate the vaccine effectiveness (VE) and impact of ABRYSVO vaccination during pregnancy in a real-world population over multiple seasons, which began in 2024 across Argentina and beginning in 2025 in Uruguay. We will use three retrospective design approaches in this study: (i) a test negative design (TND) to evaluate real-world VE of maternal ABRYSVO against RSV-associated outcomes in infants; (ii) a descriptive cohort design to evaluate the clinical evolution of infants hospitalized with RSV-positive lower respiratory tract disease (LRTD); and (iii) an ecologic before-and-after design to evaluate the impact of ABRYSVO vaccination during pregnancy on infant RSV-associated and all-cause respiratory outcomes.

Eligibility overview

Sex: ALL

Age: 0 Years to 24 Months

Healthy volunteers: No

Study type: OBSERVATIONAL

Eligibility criteria

Test Negative Design Inclusion Criteria:

1. Infants ≤9 months (≤270 days) of age on the index date.
2. Index date within the time period for data collection (approximately 01 April to 30 September in 2024, 2025, or 2026).
3. Infants born at 32 weeks of gestational age or greater.
4. Hospitalized for at least 24 hours with LRTD (symptoms related to LRTD might be absent at the time of admission but if they develop within the first 24 hours of hospitalization, the criteria for LTRD will be considered met), and specimen collected for RSV within 10 days prior to hospital admission through 3 days after a hospital admission through SOC testing.
5. Infant date of birth 14 days or more after start of the first seasonal ABRYSVO vaccination campaign, to ensure potential to have been born to an ABRYSVO-vaccinated individual.
6. Infant born to individuals who were expected (based on estimated date of delivery) to reach the indicated ABRYSVO vaccination window (320/7 to 366/7 weeks' gestation) during a local ABRYSVO vaccination season.

Test Negative Design Exclusion Criteria:

1. Received any licensed or investigational RSV preventive product (e.g., Palivizumab, Nirsevimab, active RSV vaccine) since birth.
2. Received ≥1 blood transfusion or other blood products containing antibody (e.g., fresh frozen plasma) since birth.
3. Born to individual who received any other licensed or investigational RSV vaccine during pregnancy.
4. Born to individual for whom ABRYSVO vaccination status cannot be confirmed in available data sources.
5. Infants with LRTD that require hospitalization for reasons other than clinical criteria (e.g., for social reasons, other medical condition in an infant with LRTD without hospitalization criteria).

Cohort Design Inclusion Criteria:

1\. RSV positive cases ≤9 months of age from the TND study.

Cohort Design Exclusion Criteria: None.

Ecologic Before-and-After Design Inclusion Criteria:

1. Infants and children ≤24 months of age on the index date.
2. Index date during the calendar years for data collection (pre- or post-ABRYSVO program implementation.
3. Meets ≥1 outcome definition during the time period for data collection.

Ecologic Before-and-After Design Exclusion Criteria: None.

Locations (1)

Buenos Aires, Argentina