An investigational recombinant pertussis toxin elicited better antibody responses in acellular pertussis-primed adolescents compared with the currently licensed chemically detoxified pertussis toxin vaccine, according to data published in AAP Grand Rounds.

Using a randomized controlled trial, investigators from multiple institutions compared the immunogenicity of a recombinant acellular pertussis vaccine that used genetically detoxified pertussis toxin and filamentous hemagglutinin with that of a licensed acellular pertussis vaccine that used chemically detoxified pertussis toxin (Tdap) in previously immunized teens. Healthy adolescents in Geneva, Switzerland, aged 11 to 15 years who had received 5 previous acellular pertussis immunizations were randomly assigned to receive recombinant acellular pertussis and tetanus-diphtheria vaccines or chemically detoxified Tdap.

A total of 60 teenagers were enrolled: 31 participants received the recombinant acellular pertussis vaccine and tetanus-diphtheria vaccine and 29 received chemically detoxified Tdap. Antibody levels were found to be increased in both groups by day 28; however, levels of pertussis toxin neutralizing and pertussis toxin immunoglobulin (Ig) G antibodies were significantly higher in those who received recombinant acellular pertussis vaccine (P =.016) and tetanus-diphtheria vaccine (P =.0006) compared with chemically detoxified Tdap. No significant differences were seen in levels of filamentous hemagglutinin, diphtheria toxoid, or tetanus toxoid antibodies between groups at 28 days.

Pertussis toxin neutralizing and pertussis toxin IgG seroresponse rates at day 28 were also higher in the recombinant acellular pertussis vaccine and tetanus-diphtheria groups compared with the group who received chemically detoxified Tdap (97% and 97%, respectively, vs 79% and 93%, respectively). By day 365 following immunization, antibodies for filamentous hemagglutinin, tetanus toxoid, and diphtheria toxoid declined to similar levels in both groups but pertussis toxin neutralizing and pertussis toxin IgG seroresponse rates were 79% and 71%, respectively, in the recombinant acellular pertussis vaccine and tetanus-diphtheria vaccine groups compared with 39% and 39%, respectively, among those in the chemically detoxified Tdap group (P =.006 and P =.03, respectively).

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According to the investigators, the recombinant acellular pertussis vaccine induces higher levels of antipertussis toxin antibodies compared with currently licensed options. They also noted, however, that this candidate pertussis vaccine may also require earlier, repeated booster or a stronger adjuvant because pertussis toxin neutralizing and pertussis toxin IgG seroresponse rates to recombinant acellular pertussis vaccine at 1 year were only 79% and 71%, respectively.

Reference

Brady R. Chemically detoxified versus recombinant pertussis toxin vaccines. AAP Grand Rounds. 2019;42:6.