Meningitis is a major public health problem that affects 2.5 million people worldwide each year.
This disease is caused by inflammation of the meninges, which are the tissues that surround the brain and spinal cord. It can be caused by non-infectious processes (autoimmune disorders, cancer, drug reactions) or infectious processes (bacteria, viruses, fungi and, less frequently, parasites). It affects all ages, although children under 5 years old are the main risk group for this pathology, which can be fatal.
Epidemiology of meningitis
Although viral meningitis is relatively common, the really dangerous ones are those of bacterial origin, which can cause death in just 24 hours. One in ten people who get bacterial meningitis die.
There are several bacteria that can cause this type of meningitis, however, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis (N. meningitis) are the most common and are transmitted from person to person through droplets of respiratory or throat secretions.
Bacterial meningitis can cause brain damage, hearing loss, or learning problems in 10% to 20% of survivors. A less common, but even more severe (and often fatal) form of meningococcal disease is meningococcal septicemia, which is characterized by a hemorrhagic rash and rapid circulatory collapse.
The key is to vaccinate:
Moving towards “a world without meningitis”, as the WHO has proposed for 2030, involves achieving three main objectives:
- eliminate epidemics of bacterial meningitis.
- reduce the number of cases of preventable bacterial meningitis by 50%, and deaths by 70%, through vaccination.
- strive to reduce disability and improve quality of life after meningitis.
The incidence rate of pneumococcal meningitis in the global population in 2022 was 0.3/100,000 inhabitants, similar values to those recorded in the years 2015-2016.
The low vaccination coverage recorded in recent years generated an accumulation of susceptible people that favors the re-emergence and appearance of outbreaks due to this disease. When vaccination coverage drops, cases increase because bacteria find niches to survive.
Bacterial meningitis is present worldwide, but the greatest burden of disease is seen in a region of sub-Saharan Africa, known as the African Meningitis Belt, which is recognized as particularly high risk for epidemics of meningococcal and pneumococcal meningitis, and where such epidemics usually follow a seasonal pattern (generally from January to June), with growth that varies from one year to the next. Licensed vaccines against meningococcal, pneumococcal, and haemophilus influenzae diseases have been available for many years. These bacteria have several different strains (known as serotypes or serogroups) and vaccines are designed to protect against the most harmful strains.
Over time, there have been significant improvements in strain coverage; In October 2023, Pfizer introduced Penbraya - the first FDA-approved 5-in-1 meningococcal vaccine - providing adolescents and young adults with the most complete protection available against the leading causes of the disease.
Today is an important turning point, as this pentavalent vaccine has the potential to completely change the landscape of meningitis vaccines.