Reducing the spread of meningococcal bacteria

A recent UK study has discovered that two new vaccines can reduce the transmission of meningococcal bacteria which can cause meningitis and other life-threatening illnesses. The study was led by the University of Southampton and took place in 10 centres across the UK, including the Oxford Vaccine Group.

Meningococcal bacteria cause a range of serious diseases. The bacteria are commonly carried in the throat, and can pass from person to person. Up to 11% of adults carry the bacteria harmlessly without any signs or symptoms of meningococcal disease, and in teenagers the carriage rate may be as high as 25%. It is not fully understood why disease develops in some individuals but not in most people. There are 13 different types of meningococcal bacteria; the most common in the UK are ‘group’ B, C, Y, and W.

The most direct way to protect individuals against meningococcal disease is through vaccination. At the moment only group C is routinely protected against by vaccination in the UK, although a new vaccine to protect against group B was recently recommended for introduction into the UK schedule. As well as individual protection, if enough people are vaccinated, rates of carriage of the bacteria in the throat might fall, so that there is less chance of transmission. With fewer bacteria around, even the unvaccinated are protected (through herd immunity).

The Southampton study set out to test whether two new meningococcal vaccines could reduce carriage of the bacteria in a group of university students aged 18 to 24. One of the vaccines tested was the new MenB vaccine (4CMenB); the other was a vaccine that protects against types A, C, W and Y (MenACWY-CRM). Three months after vaccination MenACWY-CRM had reduced carriage rates by 39 per cent, while 4CMenB had reduced carriage rates overall by between 20 and 30 per cent.

Robert Read, Professor of Infectious Diseases at the University of Southampton, who led the study, said: “This is a significant piece of work in helping more and more people be protected from meningitis. We have shown that vaccines modify the way the bacteria are carried, so even when the antibodies are no longer present in the blood, the carriage in the throat is still prevented, and so is onward transmission of the infection to others. This could provide a degree of herd protection against meningitis if implemented in a campaign in which high transmission occurs, for example in teenagers and young adults.”

More information on meningococcal disease, the MenC vaccine and the new MenB vaccine.

Read the abstract of the Southampton study .