Generality
The " meningococcal B vaccine " is a non-compulsory vaccination that guarantees immunity against meningitis caused by the homonymous bacterium (meningococcus B).
What is the meningococcus B vaccine?
The meningococcus B vaccine, also known as anti-meningococcal vaccination B, is the vaccine preparation that prevents meningitis due to the meningococcus B bacterium ; the latter represents a subtype (or serotype) of the famous bacterial species Neisseria meningitidis .
In Italy, the usual meningococcal B vaccine is the pharmaceutical preparation known as Bexsero ; consequently, the information present in the subsequent passages of this article refer specifically to the latter.
What are meningococcal B meningitis and meningitis?
The term meningitis identifies an inflammatory process affecting the meninges ; in number 3, the meninges are the membranes that cover and protect the brain and the spinal cord, that is the two main components of the central nervous system of the human being.
The possible causes of meningitis are numerous; in fact, to cause inflammation of the meninges can be infectious agents, such as viruses, bacteria or fungi, physical injuries involving the central nervous system, some types of drugs, some brain tumors and certain systemic diseases.
Curiosity: when is a meningitis defined infectious?
In the medical field, meningitis due to an infectious agent - be it a virus, a bacterium or a fungus - is called infective meningitis .
Infectious meningitis is, by far, the most common and clinically interesting episodes of inflammation of the meninges.
MENINGOCOCCUS MENINGITIS B
Meningococcal B meningitis is one of the most important examples of bacterial meningitis ; bacterial meningitis are very feared conditions and constitute a serious danger for human beings, as they can give rise to serious and sometimes deadly consequences (eg, septicemia, encephalitis and / or myelitis).
The symptomatology of meningococcal B meningitis is quite extensive and includes: high fever, vomiting, confusion, irritability, neck stiffness, photophobia, headache, drowsiness, pallor, convulsions and epilepsy.
According to the most reliable epidemiological data, worldwide, the annual number of meningococcal B meningitis cases would fluctuate between 20 thousand and 80 thousand and the mortality rate would be 10%.
Curiosity: which are the subtypes of Neisseria meningitidis most important for human beings?
According to the most recent studies, there are 13 subtypes (or serotypes) of Neisseria meningitidis ; of these subtypes, the most important for human beings, as they can cause serious diseases such as meningitis, are: meningococcus A, the aforementioned meningococcus B, meningococcus C (see meningococcus vaccine C), meningococcus W135 and the meningococcus Y.
Indications
The meningococcus B vaccine is a highly recommended practice for all those at risk of meningococcal B meningitis; among the latter, include:
- newborns,
- children under the age of 5,
- immunosuppressed like AIDS patients,
- carriers of chronic diseases that favor the onset of infections (eg: diabetics, liver patients etc.)
- all those who, for a wide variety of reasons, must travel to countries where meningococcal B meningitis is a widespread infection.
For reasons that can be easily understood, among those at risk, those who arouse the greatest interest and who represent the most numerous portion are infants and children.
Perhaps not everyone knows that, in Italy, meningococcus B is responsible for at least 80% of cases of pediatric meningitis.
Method of administration
The mode of administration of the meningococcal B vaccine is only one and consists of so-called deep intramuscular injection .
Regarding the site of this injection, this varies according to the age of the subject subjected to vaccination; in fact, if for infants under 12 months, it consists of the anterolateral portion of the thigh, for children from 12 months upwards, for adolescents and adults it consists of the deltoid region of the shoulder .
Dosage in young and very young
In subjects of young age (infants and children), the administration of the meningococcus B vaccine involves a series of dosages and boosters, therefore it does not consist of a single injection, but of several injections .
The precise number of dosages and recalls varies according to the age of the individual, here is how:
- If the person who receives the meningococcus B vaccine is less than 6 months, 3 dosages are expected within the year of life, practiced at least one month apart from each other, and a recall within 2 years;
- If the person who receives the meningococcus B vaccine has between 6 and 12 months, 2 dosages are expected within the year of life, practiced no less than 2 months apart from each other, and a recall during the 2 Year of life;
- If the person receiving the meningococcus B vaccine is between 1 and 2 years of age, 2 dosages are foreseen, practiced no less than 2 months apart from each other, and a booster during the 2nd year of life;
- If the person receiving the meningococcus B vaccine is a child older than 2 years and less than 11 years, 2 dosages are foreseen, practiced no less than 2 months apart from each other, without any recall.
Dosage in adolescents and adults
As regards adolescents (11 or more years) and adults, the administration of the meningococcus B vaccine involves 2 dosages, practiced at least one month apart from each other, without any recall.
| Table. Summary of dosages of meningococcus B vaccine based on age groups. | |||
| Age range | Number of dosages | Time interval between one dosage and another | Recall? |
| 2-5 months of life | 3 | Not less than a month | Yes, between the 12th and 15th month of life. A delay up to the 24th month of life is allowed. |
| 6-11 months of life | 2 | Not less than two months | Yes, between the 12th and 23rd month of life. In any case, it is important that they spend at least two months from the second dosage. |
| 12-23 months of life | 2 | Not less than two months | Yes, within the 2nd year of life. |
| 2-10 years of life | 2 | Not less than two months | No, but it needs to be clarified whether it is actually needed. |
| More than 11 years of life | 2 | Not less than a month | No, but it needs to be clarified whether it is actually needed. |
Meningococcal B vaccine in adults: when is it recommended?
Adults receive the medical recommendation to undergo the meningococcus B vaccine when:
- They exhibit congenital or acquired immunodepression (reduced immune defenses);
- They are suffering from a disease, such as diabetes or thalassemia, which exposes them to contract infections more easily;
- They have to travel to a region of the world, where meningococcal B meningitis is quite widespread (so there is a significant risk of contracting it).
Meningococcal B vaccine and mandatory in Italy
In Italy, on the basis of what the new law concerning mandatory vaccines states, the meningococcus B vaccine is not a mandatory practice, but only recommended .
With regards to this topic, it is useful to recall in full what the aforementioned law affirms, which came into force on 28 July 2017: “The following vaccinations are offered free of charge and actively by the Regions:
- Anti-meningococcal vaccination B
- Anti-meningococcal vaccination C
- Anti-pneumococcal vaccination
- Rotavirus vaccination
These vaccinations are offered by the Regions and the Autonomous Provinces, based on the indications of the vaccination calendar relative to the year of birth. Then:
- Those born in 2017 are offered free anti-meningococcal B, anti-meningococcal C, anti-pneumococcal and anti-rotavirus vaccinations
- Those born between 2012 and 2016 are offered free anti-meningococcal C and anti-pneumococcal vaccinations "
For more information on mandatory vaccines in children, readers are encouraged to consult this article.
Composition
Like any vaccine, the meningococcus B vaccine also contains a component called " active ", which in this case serves to guarantee immunity against meningitis caused by meningococcus B, and a component classified as " auxiliary ", which consists of the so-called excipients .
Active component: what does it contain?
The active component (or active ingredient) of the meningococcus B vaccine contains 4 elements combined together, which are:
- Three typical proteins present on the surface of all subtypes of Neisseria meningitidis . Specifically, these proteins are the neisseric adhesin A (NadA), the H factor binding protein (fHBP) and the neisseric heparin binding antigen (NHBA).
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- The outer membrane of meningococcus B in vesicles . This constituent element is also known by the acronym OMV, English acronym of Outer Membrane Vesicles ( Vesicles of the Outer Membrane ).
It is important to point out that the aforementioned 4 active elements belong to dead bacteria and have all been properly processed in the laboratory, so as not to cause an infection in any way, but only to stimulate a response from the immune system.
Auxiliary component: what are the excipients?
The excipients are substances that complete a pharmaceutical preparation, without having any therapeutic role.
In the case of the meningococcus B vaccine, the main excipients are:
- Aluminum hydroxide;
- Sodium chloride;
- Sucrose;
- histidine;
- Escherichia coli .
Remember that ...
The excipients present in the pharmacological preparations are not negligible, as they can cause allergic reactions.
operation
The meningococcus B vaccine protects against meningitis caused by meningococcus B, because, in the person to whom it is injected, it stimulates the immune system to produce antibodies against the aforementioned bacterial infectious agent (ie meningococcus B).
Adverse effects
The meningococcal B vaccine is well tolerated; however, it can happen that, in certain subjects, it gives rise to problems that can be qualified with the name of side effects or adverse effects .
Possible side effects of the meningococcus B vaccine include:
- Fever in the first 24 hours following the vaccine injection. Of little clinical relevance and of short duration, it represents the most common side effect of the meningococcus B vaccine;
- Redness, pain, swelling and / or soreness at the injection site. If they occur, these disorders usually occur 48 hours after the vaccine was made;
- Irritability;
- Fatigue;
- Hoarseness;
- Pallor;
- Palpitations;
- Allergic reaction against one of the vaccine components. More than a side effect, it is a complication, which, fortunately, takes place very rarely.
In general, subjects with an allergy to the meningococcus B vaccine have this problem, with symptoms and characteristic signs, after a few tens of minutes from the time of injection.
Symptoms and signs of allergic reactions caused by the meningococcus B vaccine
The typical symptoms of a possible allergic reaction against the meningococcus B vaccine may consist of:
- Itchy rash of the skin;
- Shortness of breath and severe breathing difficulties;
- Swelling of the face;
- Swelling of the tongue.
A useful remedy against some adverse effects: paracetamol
The use of paracetamol is quite common in those young people who receive the meningococcal B vaccine, as the latter is able to:
- Prevent fever;
- Accelerate the resolution of adverse effects such as redness and soreness at the site of infection.
Contraindications
The meningococcal B vaccine has some contraindications; in fact, it is not suitable for:
- Subjects with an allergy to one of the vaccine components;
- Subjects with an ongoing infectious disease. This is a temporary ban, which ends at the time of recovery from the aforementioned infectious disease;
- Individuals with a febrile syndrome in place. This is also a temporary contraindication, which ends with the resolution of the fever.
Meningococcal B vaccine and pregnancy
Although further studies are needed, pregnancy does not seem to be a contraindication to the meningococcus B vaccine.
In any case, it is good practice for a pregnant woman willing to undergo the meningococcus B vaccine to ask her doctor's advice and the gynecologist who is treating her about her wishes.
Results
Studies conducted so far indicate that the meningococcal B vaccine is significantly effective; in other words it is able to protect from the meningococcus B in a more than satisfactory way.
What are the limits of the meningococcus B vaccine?
There are numerous strains of meningococcus B; the meningococcal B vaccine protects from most of these strains, but not all, and this represents its most relevant limitation.
Another noteworthy limitation of the meningococcal B vaccine is its potential ineffectiveness in immunosuppressed subjects.
