Interview – Fatima Ait El Belghiti, scientific project manager at Santé publique France, closely monitors this evolution that is « expected but surprising in its rapidity. » She explains the causes of this dynamic and the measures to be taken.
Recently, the French population has been alerted by health authorities about a sharp increase in whooping cough, with 7,000 cases reported since the beginning of the year – compared to 495 cases in the entire year of 2023. Caused by a bacterium, this disease causes a characteristic cough (resembling the « rooster’s crow »), which contributes to its high contagiousness (the pathogen is transmitted through the air). Fatima Ait El Belghiti, scientific project manager at Santé publique France, closely monitors this « expected but surprising evolution due to its rapidity. » She explains the causes and the preventive measures that can be taken.
LE FIGARO – Is it normal to observe a sudden peak in cases of whooping cough this year in France?
Fatima AIT EL BELGHITI – Since the establishment of the whooping cough monitoring system in 1996, between 7 and 8 peaks of whooping cough have been observed every 3 to 5 years. The cycles repeat themselves but are not the same, as they can last from a few months to a year, and the number of cases varies from one cycle to another. Since 2016, we have noticed that these epidemic peaks occur more frequently in spring and summer. We are currently experiencing an expected whooping cough peak. However, the magnitude and rate of acceleration of the disease this year are surprising.
Do we have an explanation for this?
The current epidemic peak of whooping cough was expected in 2021, but it was delayed by the implementation of barrier gestures during the Covid-19 pandemic. The lower circulation of the pathogen has generated a kind of « immunity debt ». Our protection system has been less exposed to whooping cough, which functions like a software that needs updates to remain effective. Ultimately, organisms less well-equipped against the bacterium are more likely to circulate it.
Why, despite vaccination, do children often develop whooping cough shortly before the 6-year or 11-13-year booster shots?
The whooping cough vaccine is very effective and the vaccination coverage in France is good. However, since the 2000s, the vaccine used in France has been changed: we switched from a whole-cell vaccine, which caused undesirable side effects, to an acellular vaccine. Both products are equally effective, but the latest version, acellular, provides a shorter duration of protection than the whole-cell vaccine. An increase in cases of whooping cough was therefore expected just before the boosters. However, it is not considered to advance them in time because the whooping cough vaccines are pentavalent or hexavalent, immunizing the body against five to six diseases at the same time (tetanus, diphtheria, polio…). The vaccination schedule takes into account all of these pathologies. Measures to curb the whooping cough epidemic must therefore be found elsewhere. Checking one’s vaccination status and applying barrier gestures (wearing a mask, maintaining distance) in case of confirmed infection is the best way to protect young children, who are also the most vulnerable. Whooping cough can be fatal in babies under 12 months. Some adults believe they are protected when they have received a dose of a trivalent vaccine, which does not contain the whooping cough booster. Pregnant women are also advised to get vaccinated between the 20th and 36th week of pregnancy, as this will protect their child: antibodies are able to cross the placenta.
Do we have an idea of the future evolution of this epidemic wave in France?
The acceleration of contaminations puts us in a state of absolute vigilance, especially as the number of deaths due to whooping cough is increasing. We therefore ensure that we have an adequate stock of antibiotics against the disease. We know that we are currently only seeing the tip of the iceberg because not all cases are reported; therefore, it is impossible to say at this time when the peak will be over. Moreover, the current progression of whooping cough in a large part of Europe associated with the flow of visitors during the Olympic and Paralympic Games could lead to a wider spread of the bacterium.
