Whooping cough: a new nasal vaccine promises better efficacy

Respiratory infectious disease caused by bacteria Bordetella pertussis, pertussis affects 24 million children under the age of 5 per year and still causes 160,700 deaths in developing countries. A vaccine exists, dCaT, but the immunity it confers decreases over time.

In addition, while it helps prevent the onset of symptoms, it cannot prevent infection or its transmission. But a new nasal vaccine developed by an international research team led by Inserm at the Center for Infection and Immunity in Lille, the BPZE1 vaccine would induce consistent immunity in the nasal mucosa in addition to the blood immunity. The results of their work are published in The Lancet.

A bacterial barrier directly in the nose

Inserm published on March 10 the good results of their phase 2 clinical trial involving 300 healthy adult Americans.

First, the participants were divided into 2 groups. The first received a dose of BPZE1 nasally and a placebo intramuscularly. The second an intramuscular injection of the dCaT vaccine and a nasal placebo. Three months later, half of the participants in each of the two groups were given a dose of BPZE1 (to simulate a natural infection in an attenuated way), while the other half received the intranasal placebo.

The research team found several interesting effects:

• Where the dTaP vaccine did not induce secretion of markers of immunity against Bordetella pertussis that at the blood level, the nasal vaccine induced a consistent immunity at the level of the nasal mucosa in addition to the blood immunity;
• In the 28 days following the second nasal administration, 90% of participants who initially received BPZE1 had no nasal bacterial colonies;
• In the remaining 10%, colonization was low (less than 260 colonies per mL of mucus). In comparison, 70% of patients vaccinated with dCaT had significant nasal bacterial colonization (nearly 14,325 colonies per mL);
• The infection regressed faster in those vaccinated with BPZE1, and the research team found no noticeable side effects from the vaccination over the duration of the study.

A vaccine to be tested now on children

Thus, according to the study conducted and made public, this nasal vaccine would allow protection directly in the respiratory tract, a first. “Bordetella pertussis infecting the respiratory tract and multiplying in their mucous membranes, immunity at this level could indeed be essential in the prevention of whooping cough epidemics” says the Inserm press release.

As the participants in this study are all adults over the age of 18, another study is underway to more specifically assess the efficacy and safety of BPZE1 in school-aged children, a critical location for disease transmission.