title: Maternal Immunization Earlier in Pregnancy Maximizes Antibody Transfer and Expected Infant Seropositivity Against Pertussis.
abstract: BACKGROUND
  Maternal immunization against pertussis is currently recommended after the 26th gestational week (GW). Data on the optimal timing of maternal immunization are inconsistent.
  
  
  METHODS
  We conducted a prospective observational noninferiority study comparing the influence of second-trimester (GW 13-25) vs third-trimester (≥GW 26) tetanus-diphtheria-acellular pertussis (Tdap) immunization in pregnant women who delivered at term. Geometric mean concentrations (GMCs) of cord blood antibodies to recombinant pertussis toxin (PT) and filamentous hemagglutinin (FHA) were assessed by enzyme-linked immunosorbent assay. The primary endpoint were GMCs and expected infant seropositivity rates, defined by birth anti-PT >30 enzyme-linked immunosorbent assay units (EU)/mL to confer seropositivity until 3 months of age.
  
  
  RESULTS
  We included 335 women (mean age, 31.0 ± 5.1 years; mean gestational age, 39.3 ± 1.3 GW) previously immunized with Tdap in the second (n = 122) or third (n = 213) trimester. Anti-PT and anti-FHA GMCs were higher following second- vs third-trimester immunization (PT: 57.1 EU/mL [95% confidence interval {CI}, 47.8-68.2] vs 31.1 EU/mL [95% CI, 25.7-37.7], P < .001; FHA: 284.4 EU/mL [95% CI, 241.3-335.2] vs 140.2 EU/mL [95% CI, 115.3-170.3], P < .001). The adjusted GMC ratios after second- vs third-trimester immunization differed significantly (PT: 1.9 [95% CI, 1.4-2.5]; FHA: 2.2 [95% CI, 1.7-3.0], P < .001). Expected infant seropositivity rates reached 80% vs 55% following second- vs third-trimester immunization (adjusted odds ratio, 3.7 [95% CI, 2.1-6.5], P < .001).
  
  
  CONCLUSIONS
  Early second-trimester maternal Tdap immunization significantly increased neonatal antibodies. Recommending immunization from the second trimester onward would widen the immunization opportunity window and could improve seroprotection.
authors.affiliation: Center for Vaccinology and Neonatal Immunology, Department of Pediatrics and Pathology-Immunology.|Departments of Neonatology and Pediatric Intensive Care.
authors.forename: Christiane S
authors.initials: CS
authors.lastname: Eberhardt
authors.affiliation: Pediatrics, Children's Hospital of Geneva.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Blanchard-Rohner
authors.affiliation: Centerfor Vaccinology and Neonatal Immunology, Department of Pediatrics and Pathology-Immunology.
authors.forename: Barbara
authors.initials: B
authors.lastname: Lemaître
authors.affiliation: Department of Gynecology and Obstetrics.
authors.forename: Meriem
authors.initials: M
authors.lastname: Boukrid
authors.affiliation: Clinical Research Center, University Hospitals of Geneva and Faculty of Medicine, University of Geneva, Switzerland.
authors.forename: Christophe
authors.initials: C
authors.lastname: Combescure
authors.affiliation: Department of Gynecology and Obstetrics.
authors.forename: Véronique
authors.initials: V
authors.lastname: Othenin-Girard
authors.affiliation: Department of Gynecology and Obstetrics.
authors.forename: Antonina
authors.initials: A
authors.lastname: Chilin
authors.affiliation: BioNet-Asia Co, Ltd, Bangkok, Thailand.
authors.forename: Jean
authors.initials: J
authors.lastname: Petre
authors.affiliation: Department of Gynecology and Obstetrics.
authors.forename: Begoña Martinez
authors.initials: BM
authors.lastname: de Tejada
authors.affiliation: Center for Vaccinology and Neonatal Immunology, Department of Pediatrics and Pathology-Immunology.|Pediatrics, Children's Hospital of Geneva.
authors.forename: Claire-Anne
authors.initials: CA
authors.lastname: Siegrist
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology*; D001886:Bordetella pertussis / Q000276:immunology*; D005260:Female; D006801:Humans; D007112:Immunity, Maternally-Acquired / Q000276:immunology*; D007114:Immunization / Q000706:statistics & numerical data*; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000517:prevention & control; D010567:Pertussis Vaccine / Q000008:administration & dosage* / Q000627:therapeutic use; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control; D011446:Prospective Studies; D013997:Time Factors; D014917:Whooping Cough / Q000276:immunology* / Q000517:prevention & control*
chemical_list: D000907:Antibodies, Bacterial; D010567:Pertussis Vaccine
keywords: maternal antibodies; maternal immunization; neonates; pertussis; pregnancy