Vaccination is the most effective way to prevent whooping cough. But currently available vaccines have only limited efficacy. This is why Dr. Camille Locht and his team at the Center for Infection and Immunity in Lille are working on developing an intranasal vaccine which – for the moment – has proven itself in the laboratory. The scientist tells us about this research.
Pertussis is an infectious respiratory disease caused by bacteria Bordetella pertussis. Very contagious, it is known to cause fatal complications in infants. Since the end of the 1990s, the dCaT vaccine has mainly been used to prevent the disease. But as Dr. Camille Locht explains to us, “if effective against symptoms, this vaccine does not prevent transmission – or only minimally – and the immunity it confers is only short-lived“
Under these conditions, why do current vaccination recommendations encourage those around a newborn to be vaccinated if immunization does not prevent transmission? In fact, transmission is human-to-human and occurs through droplets from the nose or mouth during coughing. “Encouraging those around you to get vaccinated is what is called ‘Cocooning’, i.e. vaccinating the whole family cocoon and loved ones to prevent them from developing symptoms and to the child to fall ill.”
Fight against transmission
This is why, within the Center for Infection and Immunity in Lille, Dr. Locht’s team is working on the development of a new pertussis vaccine. So they developed a so-called “attenuated” vaccine because it contains an attenuated version of the bacteria. Baptized BPZE1, it has the particularity of being administered nasally and thus of “mimic the natural modes of transmission and colonization of Bordetella pertussis“.
The scientists therefore tested their vaccine on 300 adults. Divided into 2 groups, the participants received either a dose of BPZE1 by the nasal route and a placebo by the intramuscular route, or an intramuscular injection of the dCaT vaccine and a placebo by the nasal route.
Result : “where the dTaP vaccine only induced secretion of markers of immunity against Bordetella pertussis in the blood, BPZE1 induced consistent immunity in the nasal mucosa in addition to blood immunity“, underlines Inserm in a press release.
Moreover, “within 28 days of the second nasal administration, 90% of participants who initially received BPZE1 had no nasal bacterial colonies. In comparison, 70% of patients vaccinated with dCaT had significant nasal bacterial colonizationThis last point is particularly important since Bordetella pertussis infects the respiratory tract and multiplies in their mucous membranes. Immunity at this level could be essential in preventing whooping cough outbreaks.
“Bordetella pertussis being highly infectious for humans, it is critical that a vaccine not only targets the development of the disease but also the transmission of the bacteria and the rate at which the body gets rid of it“, concludes Camille Locht. “In this perspective, BPZE1 appears as a new relevant tool to prevent whooping cough infections and reduce epidemic transmission chains..”
To note As Dr. Locht’s study was conducted in adults, the next step will be to assess the efficacy and safety of BPZE1 in children.