- Design
- Phase 2b, randomised, observer-blinded, placebo- and active-controlled trial
- Population
- 366 vaccinated children aged 6 to 17 primed with acellular pertussis vaccines
- Primary outcome
- Fold rise in nasal secretory IgA to pertussis whole-cell extract at day 29
- Effect
- GMFR 3.8 (95% CI 3.1 to 4.7) with BPZE1; 3.5 (2.9 to 4.3) with BPZE1 plus Tdap
This phase 2b, observer-blinded trial at 16 sites in the UK, Australia and Costa Rica randomised 368 children aged 6 to 17, primed with acellular pertussis vaccines, to intranasal BPZE1 with placebo injection, Tdap with placebo spray, or both. The sponsor was the vaccine's developer.
The primary outcome was the fold rise in nasal secretory IgA against pertussis whole-cell extract at day 29. It was 3.8 (95% CI 3.1 to 4.7) with BPZE1 and 3.5 (2.9 to 4.3) with BPZE1 plus Tdap. Serum IgG responses to acellular antigens with the combination were comparable with Tdap alone. All participants in the Tdap groups had protective diphtheria and tetanus antibody levels.
Solicited adverse events were mostly mild or moderate (48%, 67% and 72%), with no vaccine-related serious adverse events.
This is an immunogenicity study. It does not show that the vaccine prevents pertussis or transmission.
- BPZE1 is an investigational vaccine and not available for routine use.
- Mucosal IgA rose, but no clinical protection data are reported.
- Combined with Tdap, serum responses were comparable with Tdap alone.
- Continue to follow national immunisation schedules for pertussis.
Why it matters
Current vaccines protect against disease but not clearly against colonisation, which is the gap this approach targets.
Don't overread it
Immune response is a surrogate; efficacy against infection was not tested.
The statistics, in plain English
A fold rise of 3.8 means nasal antibody rose to about four times baseline. Higher antibody does not by itself prove protection from infection or transmission.
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