Highlights
• Recombinant acellular pertussis vaccine is safe and immunogenic in pregnant women.
• Vaccine formulations containing PTgen were non-inferior to comparator vaccine.
• Low-dose ap1gen is good alternative for pregnant women when DT and TT are not needed.
Abstract
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 (PTgen) and filamentous hemagglutinin (FHA) may generate comparable anti-PT antibody concentrations, even at lower doses, to chemically inactivated acellular pertussis vaccines (Tdapchem) 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 PTgen and 1 µg FHA (ap1gen), or tetanus, reduced-dose diphtheria combined with ap1gen (Tdap1gen), or combined with 2 µg PTgen and 5 µg FHA (Tdap2gen), or with 5 µg PTgen and 5 µg FHA (TdaP5gen, Boostagen®) or comparator containing 8 µg of chemically inactivated pertussis toxoid, 8 µg FHA, and 2.5 µg pertactin (Boostrix™, Tdap8chem). 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 PTgen were non-inferior to comparator vaccine (Tdap8chem). Both ap1gen and TdaP5gen vaccines could be considered to have superior immunogenicity to Tdap8chem. Local and systemic solicited reactions were similar among all vaccine groups.
Conclusions
Vaccine formulations containing PTgen were safe and immunogenic in pregnant women. The ap1gen 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.
Read a full publication at: The Vaccine Journal
