Design: Randomised, observer-blinded, active- and placebo-controlled phase 2b trial
Population: 366 children aged 6–17 primed with acellular pertussis vaccine
Primary outcome: Fold rise in nasal secretory IgA to B pertussis at day 29
Effect: GMFR 3.8 (3.1–4.7) for BPZE1 and 3.5 (2.9–4.3) with Tdap; both p<0.0001

Current acellular pertussis vaccines protect against disease but induce little mucosal immunity, which may contribute to continued transmission. BPZE1 is a live-attenuated vaccine given intranasally to raise nasal secretory IgA against Bordetella pertussis.

In a phase 2b trial, 366 children aged 6–17 primed with acellular vaccines were randomised to intranasal BPZE1, intramuscular Tdap, or both. BPZE1 raised nasal secretory IgA to whole-cell extract about 3.8-fold alone and 3.5-fold with Tdap (both p<0.0001), and did not interfere with the serum IgG that Tdap generates. It was well tolerated, with no vaccine-related serious adverse events.

The result is immunogenicity, not protection: the trial measured antibody, not pertussis cases. Its value is in showing a mucosal response can be generated on top of existing vaccination without blunting it, which supports the larger efficacy trials needed before this reaches practice.

Intranasal BPZE1 raised nasal secretory IgA against pertussis roughly 3.5–3.8-fold in primed children.
It did not reduce the serum IgG produced by co-administered Tdap.
It was well tolerated, with no vaccine-related serious adverse events.
This is an immunogenicity result; efficacy against pertussis disease has not been shown.

Why it matters

Mucosal immunity is the gap in current pertussis vaccines, and this shows it can be added without undoing the existing schedule.

The statistics, in plain English

A 3.5–3.8-fold rise in nasal antibody is a clear immune response, but antibody is a stand-in for protection; only an efficacy trial counting infections can show whether it cuts disease or transmission.