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Aim/objective: This study investigates placental antibody transfer following recombinant pertussis vaccination in pregnancy in a real-world setting., Methods: This postmarketing observational study recruited pregnant women vaccinated with monovalent recombinant acellular pertussis (aP) vaccine (aP gen ; n = 199) or combined to tetanus-diphtheria (TdaP gen ; n = 200), or Td-vaccine only (n = 54). Pregnancy, delivery, and neonatal outcomes were assessed. Cord blood was collected postdelivery and pertussis toxin (PT)-IgG, filamentous hemagglutinin (FHA)-IgG, and PT-neutralizing antibodies (PT-Nab) were assessed., Results: No adverse pregnancy, delivery, or neonatal outcomes attributed to aP gen , TdaP gen , or Td vaccination were reported. High anti-PT antibody levels were detected in cord samples from women vaccinated with aP gen (geometric mean concentration [GMC] PT-IgG 206.1 IU/ml, 95% confidence intervals [CI]: 164.3-258.6; geometric mean titer [GMT] PT-Nab 105.3 IU/ml, 95% CI: 81.7-135.8) or TdaP gen (GMC PT-IgG 153.1 IU/ml, 95% CI: 129.1-181.5; GMT PT-Nab 81.5 IU/ml, 95% CI: 66.4-100.0). In the Td-only group, anti-PT antibodies were low (GMC PT-IgG 6.5 IU/ml, 95% CI: 4.9-8.8; GMT PT-Nab 3.8 IU/ml, 95% CI: 2.8-5.1). The same was found for FHA-IgG. Recombinant pertussis vaccination at <27 or 27-36 weeks gestation induced similar cord pertussis antibody levels., Conclusion: This first real-world study confirms that recombinant pertussis vaccination in the second or third trimester of pregnancy results in high levels of passive immunity in infants. Thai Clinical Trial Registry: TCTR20200528006., Competing Interests: Declarations of competing interest HTP, SM, WW, IKP, LF, CK, and VY are employed by BioNet. All other authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Recombinant acellular pertussis (ap) vaccines containing genetically inactivated pertussis toxin (PT gen ) and filamentous hemagglutinin (FHA) with or without tetanus (TT) and diphtheria (DT) vaccines (Td) were found safe and immunogenic in non-pregnant and pregnant women. We report here maternal antibody transfer and safety data in mothers and neonates., Methods: This is the follow up of a phase 2 trial in 2019 among 400 pregnant women who randomly received one dose of recombinant pertussis-only vaccine containing 1 µg PT gen and 1 µg FHA (ap1 gen ), or Td combined with ap1 gen (Tdap1 gen ), or with 2 µg PT gen and 5 µg FHA (Tdap2 gen ), or with 5 µg PT gen and 5 µg FHA (TdaP5 gen, Boostagen®, BioNet, Thailand) or chemically-inactivated acellular pertussis comparator (Tdap8 chem, Boostrix™, GSK, Belgium), either in the second or third trimester of gestation. IgG against PT, FHA, TT and DT were assessed by ELISA, PT-neutralizing antibodies (PTNA) by Chinese Hamster Ovary cell assay and safety outcomes at delivery in mothers and at birth., Results: Anti-PT and anti-FHA geometric mean concentration (GMC) ratio between infants at birth and mothers at delivery was above 1 in all groups. PT GMC in infants at birth were ≥30 IU/mL in all groups with the highest titers in infants found in TdaP5 gen group at birth (118.8 [95% CI 93.9-150.4]). At 2 months, PT GMC ratio to Tdap8 chem (98.75% CI) was significantly higher for TdaP5 gen (2.6 [1.7-4.0]) and comparable for other recombinant vaccines. No difference in PTNA titers at birth was observed between all groups nor between time of vaccination. Adverse events were comparable in all vaccine groups., Conclusions: BioNet licensed (TdaP5 gen and Tdap2 gen ) and candidate vaccines (Tdap1 gen and ap1 gen ) when given to pregnant women in the second or third trimester of gestation are safe and have induced passive pertussis immunity to infants., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: LF, CK, VY, SM and PHT are employed by BioNet. All other authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: Despite a decrease in infections caused by Bordetella pertussis due to COVID-19 pandemic, booster vaccination of pregnant women is still recommended to protect newborns. Highly immunogenic vaccines containing genetically inactivated pertussis toxin (PT gen ) and filamentous hemagglutinin (FHA) may generate comparable anti-PT antibody concentrations, even at lower doses, to chemically inactivated acellular pertussis vaccines (Tdap chem ) shown effective for maternal immunization., Methods: This phase 2 randomized, observer-blind, active-controlled non-inferiority trial was conducted in healthy Thai pregnant women randomly assigned to receive one dose of low-dose recombinant pertussis-only vaccine containing 1 µg PT gen and 1 µg FHA (ap1 gen ), or tetanus, reduced-dose diphtheria combined with ap1 gen (Tdap1 gen ), or combined with 2 µg PT gen and 5 µg FHA (Tdap2 gen ), or with 5 µg PT gen and 5 µg FHA (TdaP5 gen , Boostagen®) or comparator containing 8 µg of chemically inactivated pertussis toxoid, 8 µg FHA, and 2.5 µg pertactin (Boostrix™, Tdap8 chem ). Blood was collected at Day 0 and Day 28 post-vaccination. The non-inferiority of the study vaccines was assessed based on anti-PT IgG antibody levels on Day 28 pooled with results from a similarly structured previous trial in non-pregnant women., Results: 400 healthy pregnant women received one dose of vaccine. Combined with data from 250 non-pregnant women, all study vaccines containing PT gen were non-inferior to comparator vaccine (Tdap8 chem ). Both ap1 gen and TdaP5 gen vaccines could be considered to have superior immunogenicity to Tdap8 chem . Local and systemic solicited reactions were similar among all vaccine groups., Conclusions: Vaccine formulations containing PT gen were safe and immunogenic in pregnant women. The ap1 gen vaccine, with the lowest cost and reactogenicity, may be suitable for use in pregnant women when diphtheria and tetanus toxoids are not needed. This study is registered in the Thai Clinical Trial Registry (www., Clinicaltrials: in.th), number TCTR20180725004., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Librada Fortuna, Chawanee Kerdsomboon, Vilasinee Yuwaree, Souad Mansouri and Pham Hong Thai are employed by BioNet. All other authors declare no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)