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Scientists successfully test meningococcal B vaccine
Last reviewed: 01.07.2025
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This is the strain of bacteria that causes meningococcal diseases, including one of the most common forms of meningitis - inflammation of the membranes that cover the brain and spinal cord. Meningitis is caused by both viruses and bacteria, but the bacterial form (say, meningococcus B) is considered more severe, killing countless babies around the world each year.
Neisseria meningitides is a type of bacteria that causes meningococcal disease in humans. There are five common strains: A, B, C, W135, and Y, and a sixth strain, X, has recently been discovered.
The Chilean team's current work is the final stage of testing the 4CMenB vaccine for the B strain. While vaccines are currently available to combat strains A, C, W and Y, creating a vaccine for the B strain was challenging because it is actually a collection of slightly different strains. The team overcame this problem by conducting a full genomic analysis and comparing the genetic structures of the different substrains to identify common features. This allowed them to develop a broad-spectrum vaccine that includes components to attack four different parts of the bacterium.
The trial involved 1,600 children and adolescents aged 11–17 (average age 14) from twelve Chilean cities. Some of the subjects received the vaccine, while others received a placebo. One, two, or three doses of 4CMenB were administered at intervals of one, two, or six months.
Blood tests of the participants showed that those who received two or three doses of the vaccine were almost 100% protected against meningococcal B, while those who received only one dose were 92–97% protected. After six months, these figures had changed to 91–100% and 73–76% in both groups, respectively.
It remains unclear whether the vaccine provides protection against all substrains of type B and how long the effectiveness of the immune response will last. In the placebo group, 29-50% of subjects were protected against meningococcal B. No adverse effects related to the vaccine were observed in any participant.
Chilean scientists have previously found that the vaccine also provides protection to very young children. Novartis' 4CMenB is expected to hit the market in a few months.
Meningitis caused by the B strain is most common in European countries, the United States and South America.
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