The Disease: Meningococcal meningitis and meningococcal septicaemia are serious infections caused by the bacteria Neisseria meningitidis. Humans are the only known reservoir for Neisseria meningitidis.
- Meningitis: inflammation of the meninges (lining of the brain)
- Septicaemia: bacteria enters the bloodstream resulting in blood poisoning
Neisseria meningitidis is commonly found in the back of the throat or nose and will only occasionally cause disease. It is unknown why some individuals carry the bacteria without them causing harm while others go on to develop meningococcal disease.
Approximately 10% of the population will carry Neisseria meningitidis, with the highest carriage (around 25%) in 15-19 year olds. Infection is not easily spread. It is transmitted from person to person by inhaling respiratory secretions from the mouth and throat or by direct contact (kissing). Close prolonged contact is usually required to transmit the bacteria. They do not live long outside the body.
Early signs and symptoms of meningococcal disease may be non-specific and therefore difficult to distinguish from influenza or other diseases. Early symptoms include fever, vomiting, malaise and lethargy.
For decades, MenB has been the most common cause of bacterial meningitis in the UK and Ireland. Vaccines are the only way to prevent meningitis and have almost eliminated some other kinds of meningitis. Since the first meningitis vaccine was introduced against Hib meningitis in 1992, many kinds of meningitis have been reduced or have dwindled to a mere handful of cases, including Hib, MenC and pneumococcal. Thanks to meningitis vaccines, thousands of children are alive today who would otherwise have died from these deadly diseases.The Vaccine. Developing a MenB vaccine has been much more difficult – until now, protection against MenB has been a distant possibility. Meanwhile, meningococcal meningitis and septicaemia remain the leading infectious cause of death for children under five in the UK. How effective is this vaccine? The effectiveness of a vaccine is determined by many things, including how strong an immune response it produces (its ‘immunogenicity’), and how widely it covers disease-causing strains circulating in the country. Results from the vaccine trials are very encouraging, showing that the vaccine triggers a strong immune response in infants, toddlers and adolescents.
Studies of circulating MenB strains looking at how well they match the vaccine have predicted that it will cover approximately 88% of MenB circulating in the UK, and 78% of MenB in Europe over all. The actual proportion of cases prevented will depend on other things too, including how widely the vaccine is offered and taken up, whether it prevents the bacteria from being carried and passed on as well as protecting from disease, how long protection lasts, and whether it works sufficiently well in all age groups.
Safety
Is the vaccine safe? As with all drugs, vaccines can cause side effects. Vaccine side effects may include soreness/redness/swelling or hardness of skin at the injection site, fever, lack of appetite, muscle aches, irritability, sleepiness and rashes. Almost 8,000 people, including more than 5000 infants and toddlers, have had the new MenB vaccine during clinical trials.
Results from these trials have shown that Bexsero® has a good safety profile. Can Bexsero® be given at the same time as other routine vaccines?Yes, the side effects seen when Bexsero® is given with other vaccines in the routine childhood schedule are the same as those commonly seen with vaccines in general. This is also true when the vaccine is given at the same time as hepatitis B and varicella vaccines. Fever is more common in babies when Bexsero® is given alongside other vaccines although taking paracetamol after getting vaccinated (or at the same time) reduces the likelihood and severity of fever without affecting the immune response to any of the vaccines.
What are the active ingredients in the vaccine? The active ingredients that equip our immune system to fight MenB bacteria include four main components of meningococcal bacteria. Three of them are proteins found on the surface of the bacteria: Factor H Binding Protein (fHbp), Neisseria Heparin Binding Antigen (NHBA), Neisserial Adhesin A (NadA.)
These three components help meningococcal bacteria invade and survive within the human body. In vaccinated people, the immune system can recognise and ‘neutralise’ these components, so the bacteria cannot make them ill.The final ingredient is the New Zealand MenB Vaccine (MenZB) derived from the New Zealand outbreak strain of MenB (strain NZ 98/254). All of these components have been processed and inactivated and are not part of any living bacteria, but can still stimulate the immune system.
Are there any safety reasons not to have the vaccine? What about allergies? People who have previously had an anaphylactic reaction to any of the vaccine components should not get the vaccine. In addition to the active components already mentioned, the vaccine is composed of sodium hydroxide, histidine, sucrose and water. Anaphylaxis to current vaccines is very rare and is estimated to occur in one in a million doses given, although a recent study found no reports of anaphylaxis following more than 5 million preschool and infant immunisations over an entire year in the UK and Ireland.
People with severe immune system problems cannot have live vaccines, but the new MenB vaccine is not live. Those with egg allergies may need to avoid some flu vaccines, but generally food allergies are not a reason to avoid vaccination. People often worry that eczema, asthma, epilepsy and a family history of reactions to vaccinations are a reason to avoid vaccinations, but this is not true.
