A Post-Marketing Safety Study to Evaluate the Safety of Respiratory Syncytial Virus Vaccine (ABRYSVO™) Exposure During Pregnancy in an Integrated Healthcare System in the United States (C3671042)

Study type

• Study topic:
  Human medicinal product
• Study type:
  Non-interventional study
• Scope of the study:
  Safety study (incl. comparative)
• Data collection methods:
  Secondary use of data

Non-interventional study

• Non-interventional study design:
  Cohort

Study drug and medical condition

• Medicinal product name:
  ABRYSVO
• Anatomical Therapeutic Chemical (ATC) code:
  (J07BX05) respiratory syncytial virus vaccines

  respiratory syncytial virus vaccines

Population studied

• Short description of the study population:
  The study population comprises pregnant individuals aged 15 to 54 years who are members of Kaiser Permanente Northern California (KPNC) and who reach 32 weeks (32 0/7 weeks) of gestation between September 22, 2023, and September 22, 2027. Eligible participants must have had at least one prenatal visit before 20 weeks of gestation and continuous health plan enrollment with medical and pharmacy benefits from at least 90 days before pregnancy onset through delivery or pregnancy outcome. Pregnancies exposed to Respiratory Syncytial Virus Vaccine (ABRYSVO™) before 32 weeks of gestation or exposed to another Respiratory Syncytial Virus (RSV) vaccine during pregnancy are excluded. The study includes both a pregnancy cohort, consisting of eligible ABRYSVO™-exposed and unexposed pregnancies, and an infant cohort that includes all live-born infants from those eligible pregnancies. Study data are derived from routinely collected electronic medical records within KPNC, an integrated healthcare system serving more than 4.5 million members in Northern California.
• Special population of interest:
  Pregnant women

Study design details

• Study design:
  This is a retrospective, real-world, non-interventional cohort study using electronic medical record data from Kaiser Permanente Northern California to compare pregnancy, maternal, and neonatal outcomes among pregnant individuals exposed or unexposed to Respiratory Syncytial Virus Vaccine (ABRYSVO™)
• Main study objective:
  The primary objective of the study is to estimate the risk of preterm birth and hypertensive disorders of pregnancy following exposure to Respiratory Syncytial Virus Vaccine (ABRYSVO™) during pregnancy. The study compares outcomes among pregnant individuals exposed to ABRYSVO™ with those who are unexposed.
• Setting:
  The study is conducted within Kaiser Permanente Northern California, an integrated healthcare delivery system serving more than 4.5 million members. The organization maintains comprehensive electronic medical records that capture vaccination, prenatal care, delivery, maternal health, and infant health information, enabling longitudinal follow-up of pregnancies and live-born infants during routine clinical care. The study uses data collected in real-world clinical practice across Northern California and leverages the Kaiser Permanente Northern California pregnancy database and electronic medical record systems to identify exposures, outcomes, and relevant covariates.
• Comparators:
  The comparator group consists of pregnant individuals who are not exposed to ABRYSVO™. For neonatal and infant outcomes, the comparator group consists of infants from pregnancies unexposed to ABRYSVO™.
• Outcomes:
  The primary outcomes are preterm birth and hypertensive disorders of pregnancy following exposure to Respiratory Syncytial Virus Vaccine (ABRYSVO™) during pregnancy. Secondary outcomes include pregnancy-related outcomes (such as stillbirth, premature labor, premature rupture of membranes, preterm premature rupture of membranes, cesarean delivery, prolonged maternal length of stay, and placental abruption), maternal outcomes (including thrombocytopenia, Guillain-Barré Syndrome, other immune-mediated demyelinating conditions, polyneuropathies, atrial fibrillation, and all-cause maternal mortality), and neonatal/infant outcomes (including small for gestational age, large for gestational age, low birth weight, neonatal intensive care unit admission, mechanical ventilation, and neonatal death).
• Data analysis plan:
  The interim analysis will provide descriptive summaries of maternal and infant characteristics and calculate incidence rates for all primary, pregnancy-related, maternal, and neonatal/infant outcomes among Respiratory Syncytial Virus Vaccine (ABRYSVO™)-exposed and unexposed pregnancies. The final analysis will use Cox regression models for pregnancy-related and maternal outcomes and logistic regression for neonatal/infant outcomes, adjusting for relevant covariates to compare risks between ABRYSVO™-exposed and unexposed pregnancies.