Potentially fatal meningococcal meningitis has experienced an “unprecedented surge” in France following the end of health measures introduced during the Covid-19 crisis, the Pasteur Institute warned on Tuesday, calling for vaccination to be expanded to particularly affected young people.
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Meningitis is an infection of the coverings surrounding the brain and spinal cord. In most cases they are viral in nature, but can also be of bacterial origin: this is the case with meningococcal meningitis.
Transmission occurs from person to person through close, prolonged contact.
About one in ten people in the general population (but one in three adolescents) is a carrier of meningococci without showing any symptoms of the disease. However, after a respiratory infection, meningococci can spread throughout the body through the bloodstream.
High fever, severe headache, vomiting, stiff neck, sensitivity to light, red or purple spots (purpura) are the main symptoms.
This unpredictable and devastating disease can cause death in less than 24 hours without prompt treatment. With proper treatment, mortality remains at 10%.
Meningococcal meningitis can also have more or less serious consequences: amputation, deafness, cognitive impairment, learning difficulties, etc.
During the Covid-19 epidemic, barrier gestures such as wearing a mask and social distancing had positive effects on respiratory infections, recalls the Pasteur Institute. This was the case with meningococcal meningitis, where the number of infections fell by more than 75% in 2020 and 2021. However, the reference center was concerned about the future, when the protective measures would be relaxed.
Scientists closely examined the evolution of the disease between 2015 and 2022 and observed a rapid resumption of bacterial activity.
“Meningococcal meningitis experienced an unprecedented upswing in autumn 2022, with today, in autumn 2023, the number of cases being many times higher than in the period before the Covid-19 pandemic,” summarizes Samy Taha, one of the authors of a study, published together last month in the Journal of Infection and Public Health and researchers in the Division of Invasive Bacterial Infections at the Pasteur Institute.
“Never achieved” values
While 298 cases were registered between January and September 2019, 421 cases have already been registered between January and September 2023, an increase of 36%, “although the winter peak has not yet been reached,” emphasizes Pasteur.
In France, the values have “never been reached,” emphasizes Muhamed-Kheir Taha, head of the National Reference Center for Meningococci.
According to the research institute, there are essentially two explanations for this: a decrease in general immunity as a result of the decrease in the spread of strains, but also the decrease in vaccinations, which fell by 20% in the case of vaccination against meningococcal C during the first confinement, for example.
Different types of shells or capsules surround the bacteria. In the case of meningococci, the type of these sheaths is designated by letters.
Today in France, since 2018, only vaccination against meningococcal group C has been compulsory; since 2022, vaccination against meningococcal B has only been recommended for infants.
Unlike in some countries such as the UK, there are still no recommendations against groups Y and W for the general population. However, since the end of the pandemic, the latter strains have been responsible for most meningitis.
“We believe it is time to rethink the current vaccination strategy,” Muhamed-Kheir Taha told AFP.
The researchers, currently collaborating with the High Authority for Health (HAS), recommend in particular the extension of the tetravalent vaccine against meningococci groups A, C, Y and W to adolescents, the main healthy carriers of meningococci.
Especially since the recurrence of meningitis may increase in the coming months with the seasonal flu epidemic creating a “favorable context for the development of meningococcal bacteria,” particularly through increased blood flow and exposure to respiratory pathogens.
Another point of vigilance: large gatherings that favor contamination, such as the Olympic Games.