Meningococcal disease is caused by the bacterium Neisseria meningitidis. It causes a range of serious, life-threatening diseases including septicaemia (blood poisoning) and meningitis. It can affect all age groups, but the rates of disease are highest in children under five years of age, with the peak incidence in those under one year of age. There is a second peak in incidence in young people aged 15 to 19 years of age.
There are thirteen different types of the bacterium. Six of these - types A, B, C, W, X and Y - cause most of the disease cases worldwide. The most common types in the UK are B, C, W and Y. Since the MenC vaccine was introduced in the UK in 1999, there has been a big fall in cases of type C meningococcal disease (MenC). Around 90% of cases of meningococcal disease in the UK are currently caused by type B disease (MenB). Since 2009, cases of MenW disease have been on the increase in the UK.
See the Meningitis Research Foundation website for more detailed information on the signs and symptoms of meningitis and septicaemia.
Overall, 1 in 20 cases of meningococcal disease result in death; death rates are higher for teenagers and young adults. 1 in 5 survivors have permanent effects such as skin scars, limb amputation(s), hearing loss, seizures and brain damage.
Meningococcal disease is spread by prolonged, close contact with an infected person. Between 5% and 11% of adults carry the bacteria harmlessly in their throats without any signs or symptoms of the disease. In teenagers this rate rises to 25%, but the carriage rate is low in infants and young children. The number of cases of meningococcal disease peaks in the winter each year.
It is not fully understood why disease develops in some individuals but not in others. Researchers have identified risk factors including smoking, previous infection with influenza type A, and living in ‘closed’ or ‘semi-closed’ communities, such as university halls of residence or military barracks.
In the UK, three types of vaccine are offered to different age groups to protect against different types of meningococcal disease.
2. The MenB vaccine: this new vaccine protects against type B meningococcal disease. Babies receives doses at 2, 4 and 12 months old.
3. The MenACWY vaccine: this boosts protection against MenC disease and also protects against MenA, MenW and MenY disease. This vaccine is given to teenagers and student freshers.
Five year old Charlotte Nott developed septicaemia through type B meningococcal disease infection. Her mother, Jenny Daniels, talks about the impact on Charlotte and the rest of her family, and the prospect of a new MenB vaccine that will help to prevent other people going through the same experience in the future. See the Charlotte's Appeal website for more information about Charlotte.
US student Ashley Lee caught meningococcal disease shortly after starting college. She had not had the vaccine which could have prevented it. Grateful thanks to the US National Meningitis Association and Shot by Shot for permission to use this film.
Tom Newman developed meningococcal disease at university. His life was saved by a friend who recognised the symptoms of meningitis. (This film was made by Meningitis Now .)
Meningococcal disease is most often seen in infants and young children. However, there is a second peak in cases in 15-19 year olds, which is not seen in other infectious diseases. It is not known exactly what causes this. A major study, the UK Meningococcal Carriage Study 4 , is looking to see if there might be a connection with lifestyle factors such as smoking and kissing.
Overall, numbers of cases of meningococcal disease have fallen in the UK in recent years. Following the introduction of the MenC vaccine in 1999, the number of cases caused by the type C disease fell by over 90% in vaccinated groups. It also fell by around 66% in non-vaccinated groups owing to herd immunity, as fewer people were carrying the bacterium in their throats and passing it to others (see graph below). Type C infections have caused only 2 deaths in children and young people under 20 in the last 5 years, compared to 78 deaths in the single year before the vaccine was introduced.
Following the success of the UK's MenC vaccination program, type B infections account for about 85% of the cases of meningococcal disease. A total of around 750 people in the UK (mostly babies and children) were infected by MenB in 2011, and around 50 of these died. The new MenB vaccine will be introduced in September 2015 and is expected to have an impact on numbers of cases of MenB disease. The MenB vaccine will also protect babies against other types of meningococcal infection, including the MenW strain which is on the increase in the UK. This is because some of the antigens (proteins) in the MenB vaccine are found in other types of meningococcal bacteria as well.
At the moment disease cause by MenW is giving cause for concern in the UK. MenW cases in England have been increasing year-on-year, from 30 cases in 2011-12 to 210 cases in 2015-16 (cases are counted from July one year to June the next year). All cases are thought to be due to a single very aggressive strain of MenW bacteria. No other European country has reported an increase in MenW cases, and the reasons for the rise in UK cases is unknown. In response, the government decided to give the MenACWY vaccine to all teenagers and new university students. This programme started in summer 2015. See more information from Public Health England and our blog post from March 2015.
Oxford Vaccine Group (OVG) has worked on the development of MenB vaccines and run trials into their effectiveness. OVG has also run studies looking at the effectiveness of a vaccine which gives protection against strains A,C,W and Y.
Source: Public Health England