Meningitis B Vaccination in Young Children - Types, Efficacy, Side Effects

Introduction

Meningococcus (Neisseria meningitidis, Nm) causes a brain disease called meningitis. Bacterial meningitis occurs more in developing countries. It is associated with high death and disability rates. Survivors develop short and long-term neurological complications. Short term complications include seizures.

On the other hand, hearing loss, decline in mental abilities, hydrocephalus, learning disability, and epilepsy are the long-term effects. Group B meningococcal disease causes a serious and invasive disease. Although it can affect any individual, children under one year are more prone to the disease. Hence, vaccination against this strain is important to prevent complications in children.

Which Strains of Meningococcal Cause Disease in Humans?

Some people are disease carriers. They have the disease strain in the throat and nose. However, when the bacterial strain is active, it causes disease in the host. A, B, C, W, X, and Y are the six strains of the bacteria that cause most diseases. B, C, and Y cause the most serious disease. It takes close and long contact to spread disease. Nm serogroup B (NmB) is the most frequent means of the disease.

What Is the Significance of Meningococcal-B Vaccine in Children and Adolescents?

Group B meningococcal disease accounts for approximately 50 % of all cases of meningitis.

Studies have shown that there is an increased risk of developing meningitis among children and adolescents. A study revealed that college students living in residence halls were at higher risk for meningitis than other students. Before the development of conjugate meningococcal vaccines, students were advised to get the meningococcal polysaccharide vaccine. With the advent of meningococcal B vaccine (MenB), the risk of developing a serious form of meningitis has reduced.

What are the Available Meningococcal B Vaccines?

Previously, meningococcal polysaccharide vaccines were used. However, they cannot prevent NmB. It is because the structure of the NmB capsule resembles some human polysaccharides. Hence, immune tolerance develops.

1. Outer-Membrane Vesicle (OMV) Vaccines: OMV are separated from the meningococcal bacteria. Then, they are released into a growth medium. OMV vaccines are safe and effective against NmB. Detergent treatment is sometimes done to lower endotoxin (structures to protect the bacteria) activity of OMV vaccines. However, it deprives the OMV of desirable antigens. Hence, it is advised to prepare native OMV vaccines from strains that have naturally low endotoxin activity.

2. Recombinant Protein Vaccines: One of the most encouraging new protein antigens is fHbp. fHbp is a protein present in all strains of Nm. fHbp binds the human complement system and activates immunity. MenB-FHbp was licensed for use in 2014.

3. New Meningococcal B Vaccines:

• Dutch OMV Vaccine: It is a hexavalent OMV-based vaccine. It has two recombinant engineered strains. It is a safe and accepted vaccine.
• Meningococcal B Vaccine By Reverse Vaccinology: Unlike conventional methods, reverse vaccinology begins by defining the genome sequence of NmB. Then, it continues with the computer-assisted prediction of more promising antigens for a new vaccine. The first designed vaccine by this method was rMenB. 4CMenB is a new vaccine engineered by reverse vaccinology. It consists of four components. It also has fHbp. 4CMenB offers good protection against meningococcal type B disease. It has been approved for active immunization in subjects ≥ two months. The vaccine consists of aluminum hydroxide (adjuvant), sodium chloride, histidine, sucrose, and water for injection.

What Is the Recommended Immunization Schedule of 4CMenB in Infants and Toddlers?

1. In children aged two to five months, the primary immunization schedule comprises three doses with an interval of at least one month. A booster dose can be given at 12 to 23 months.

2. The schedule for unvaccinated infants aged 6-11 months consists of two doses. The doses should be separated by at least two months. A subsequent booster dose is given at two years.

3. In toddlers aged 12 to 23 months, the primary schedule has two doses. They are administered at least two months apart. A booster dose may be given 12 to 23 months after the primary dose.

4. 4CMenB can also be given along with one or more (monovalent or combination) vaccines, such as pertussis, diphtheria, Haemophilus influenzae type b, hepatitis B, pneumococcal conjugate, inactivated poliomyelitis, measles, mumps, rubella, tetanus and varicella.

There are two kinds of meningococcal vaccines that are currently given to children in India: meningococcal conjugate vaccine and MenB. In 2015, the United States (U.S.) Advisory Committee on Immunizations Practices (ACIP) provided a category B for both MenB vaccines. MenB vaccine series can be administered to adolescents and young adults from 16 to 23 years. It is because this age group is at an increased risk of contracting meningococcal infections. It is done to provide short term protection against most strains of serogroup B meningococcal disease. The preferred age for MenB vaccination is 16 to 18 years.

What Is the Efficacy of 4CMenB Against Invasive Meningococcal Disease?

The potential efficacy of 4CMenB has recently been assessed in various European countries through the Meningococcal Antigen Typing System (MATS). MATS is a regulated and reproducible vaccine antigen-specific enzyme linked immunosorbent assay (ELISA) test. It has been developed to measure the amount of each antigen expressed by a strain.

Further it measures the immunological cross-reactivity with the antigen present in the 4CMenB vaccine. In a large epidemiological survey comprising European countries (1052 B-strains), MATS analysis showed that 4CMenB could cover a significant proportion of invasive disease causing strains. The predicted coverage for all countries was 78 %. However, some variation was reported between single countries. The efficacy of 4CMenB has the potential to prevent disease caused by different serogroups.

What Are the Side Effects of Meningococcal-B Vaccine?

Side effects of meningococcal vaccines can be mild or serious.

1. Mild: Mild side effects can occur in about 50 % of the patients. These side effects are temporary and last for about one to two days.

2. Serious: These may occur within minutes to hours after the vaccination.

The signs of a serious side effect are:

• Breathing problems.

• Wheezing.

• Hoarseness of voice.

• Pale skin.

• Extreme weakness.

• Dizziness.

• Palpitations.

• Extreme skin itching.

What Are the Contraindications for a Meningococcal-B Vaccine?

The meningococcal vaccine is not indicated for the following:

1. Children who had a severe life-threatening allergy to a previous vaccine.

2. Any patient who is moderately or severely ill.

3. Guillain-Barre Syndrome (GBS): GBS is an autoimmune disorder in which the nerves get affected. It causes tingling sensation and muscle weakness. Increased incidence of GBS is reported with meningococcal vaccine use. However, the link of the disease with the vaccine is not clear.

Conclusion:

Vaccination is the foremost way to prevent meningococcal disease in children. The development and approval of 4CMenB has reduced the incidence of invasive meningitis caused by NmB. Besides, studies have shown its efficacy against many NmB strains. However, further research is needed to evaluate its capability when used widely.