Along with measles, whooping cough is one of the most contagious bacterial infections. If the complications are rarer in adults, it can be dangerous for the infant, even potentially fatal.
In a publication of the scientific journal The Lancet published on Friday March 10, an international research team led by Camille Locht – research director at Inserm at the Lille Infection and Immunity Center – showed, in a phase 2 clinical trial, the efficacy and adult safety of a new nasal pertussis vaccine.
In France, the first vaccines were widely administered from the end of the 1960s. Currently, the vaccine called dCaT remains mainly used and effectively protects against symptoms. However, the latter does not prevent the transmission of whooping cough.
Therefore, the bacteria Bordetella pertussis the source of the infection, continues to circulate throughout the world and cause epidemics. To compare, “the bacteria is transmitted three times more easily than Covid-19”, says Camille Locht.
Reduction of symptoms, and transmission
Or, “the latest clinical trial proves for the first time that, in humans, the BPZE1 vaccine prevents 90% of the transmission of infection by vaccinated people”, he rejoices. The other advantage of the vaccine under development compared to those that already exist is the duration of its effectiveness. According to the researcher, “the current vaccine provides good coverage for the first few years, but eventually immunity wanes.” The BPZE1 vaccine would make it possible to protect vaccinated persons for longer.
The latter contains an attenuated version of the bacteria that causes whooping cough, and has a particular mode of administration, in the form of a nasal spray. In addition to mimicking the modes of transmission of the bacteria in the mucous membranes and the respiratory tract, “it avoids redness or swelling due to the injection”, emphasizes Camille Locht.
Good news for newborns
While the study participants were all adults over the age of 18, the results are already good news for infants as well. “This new vaccine could prevent adults in direct contact with newborns from transmitting the bacteria that causes whooping cough”explains the research director of the study.
In the longer term, the research team wants to carry out clinical trials in order to be able – eventually – to vaccinate newborns. But if he is very confident, Camille Locht admits that he remains “still many steps to go” before going to this step. A study is underway to verify the effectiveness of the BPZE1 vaccine in children of school age, a place of high transmission of the disease.
The existing vaccine remains very effective
Only 200 people took part in this clinical trial. “It is not enough to be certain that the vaccine does not cause rare side effects”, alert the study director. So far, no side effects have been reported. Before it can be submitted for release within approximately three years, the BPZE1 vaccine must still pass several clinical trials.
Improving the vaccine could make it possible to reduce the chains of epidemic transmission but until then, Camille Locht would like to remind you that those already administered “remain very effective in protecting against symptoms of whooping cough and should continue to be used”.