Vaccination against meningococcal infection

The causative agent of meningococcal infection is meningococci - Neisseria meningitidis serogroups: A, B, C, H, I, K, L, W-135, X, Y, Z or 29E (Z), most common groups are A, B, C, Y and W-135. In Russia, Asia, Africa, meningococci of group A predominate, in Western Europe and North America - group C. Meningococci of group B cause endemic diseases and local outbreaks; in New Zealand they caused an epidemic that has lasted since 1991 with an incidence of 400-500 cases per year (per 4 million population). Vaccination against meningococcal infection in the form of polysaccharide meningococcal vaccines types A and C in individuals over 2 years of age is immunogenic and provides protection for at least 3 years (at least 2 years - in children); their epidemiological effectiveness is 85-95%.

The decline in morbidity caused by pathogens of serogroups A and C is often replaced by an increase in morbidity caused by meningococcus B. More than 300,000 cases of meningitis with 30,000 deaths are registered worldwide every year. Due to cases of pilgrims from Mecca bringing in meningococci of serogroup W 135, a vaccination that includes it is now required for the Hajj (Mencevax ACWY by GlaxoSmithKline is registered in Russia).

Patients with meningitis are infectious in the prodrome, they stop releasing the pathogen 24 hours after the start of treatment. Carriage of meningococci is the main source of infection, in the interepidemic period its frequency is less than 5%, increasing during epidemics in foci to 50% or more. It is usually short-term - less than 1 week, so treatment of carriers is inappropriate. Children under 5 years of age are most often affected.

In Russia in 2007, meningococcal infection was registered in 2680 people (1779 of them were children aged 0-14 years), 1.87 per 100,000 (in children - 8.25).

Objectives of meningococcal vaccination programs

Although the group A vaccine can be used for epidemiological indications in children after 12 months, it is not suitable for routine immunization under 2 years of age; the type C vaccine is even less immunogenic at this age.

WHO recommends polysaccharide vaccines A and C for individuals over 2 years of age in risk groups, and for mass vaccination during an epidemic, both for individual protection and to create herd immunity and reduce carriage. In Canada, universal (age 6 months - 20 years) vaccination of 1.6 million people in 1992 led to a decrease in the incidence of meningitis C from 1.4 to 0.3 (per 100,000) in 1993-1998, preventing 48 cases of meningitis in vaccinated people and 26 cases due to herd immunity. Its effectiveness was 41% in 2-9 year olds, 75% in 10-14 year olds, and 83% in 15-20 year olds, but this figure was zero in children aged 0-2 years.

Vaccination against meningococcal infection according to epidemiological indications is carried out in risk groups. Mass immunization with vaccine A + C (with coverage of at least 85%) is carried out when the incidence rate rises above 20.0 per 100,000 population. Vaccination is also carried out in foci of infection. Children with asplenia or removed splenitis, with cerebrospinal fluid rhinorrhea, after cochlear implantation surgery, as well as with a number of forms of primary immunodeficiency (deficiency of complement components C3-9) are at particular risk.

A conjugate vaccine of type C has been created and is used in Europe (schedule - 2-3-4 months, together with other vaccines), this has led to a sharp decrease in the incidence of meningitis C, this vaccination has been included in the calendars of England, Holland and Spain.

In the United States, the 4-valent conjugate vaccine Menactra™ (serotypes A, C, Y, W-135) from Sanofi Pasteur is used from age 11 years; its purpose is to reduce the incidence of meningitis in adolescents, especially college freshmen, who have outbreaks of meningitis. The vaccine is not sufficiently immunogenic in infancy; a new version of the vaccine, MenACWY, however, has shown 80% immunogenicity after 3 vaccinations starting at age 3 months, and 85% after a booster at age 1 year.

Polysaccharide vaccines of type B have common antigenic determinants with brain tissue, causing complications. Vaccines of group B are created on the basis of proteins of the outer membrane of meningococci; these vaccines are immunogenic, but only in relation to the strains of the pathogen used in its production. Such vaccines from local strains are used in Norway and New Zealand.

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Vaccination against meningococcal infection: characteristics of the drugs

The following meningococcal vaccines are registered in Russia:

Meningococcal vaccines registered in Russia

Vaccine	Compound	Dosages
Meningococcal A vaccine, Russia;	Serogroup A polysaccharides	1 dose - 25 mcg (0.25 ml) for children 1-8 years old and 50 mcg (0.5 ml) for persons 9 years old and older.
Meningo A+S Sanofi Pasteur, France	Lyophilized polysaccharides of serogroups A and C	1 dose - 50 mcg (0.5 ml) for children from 18 (according to indications from 3) months and adults
Mencevax ACWY polysaccharide - GlaxoSmithKline, Belgium	In 1 dose (0.5 ml) 50 mcg of polysaccharides of type A, CW-135.Y.	1 dose - 0.5 ml for children over 2 years old and adults
Menugate Novartis Vaccines and Diagnostics GmbH & Co., KG, Germany (in the registration phase)	1 dose (0.5 ml) contains 10 mcg of type C oligosaccharides conjugated with protein 197 of C. diphteriae. No preservatives.	For children 2 months and older and adults, it is administered intramuscularly, unlike non-conjugated vaccines, it creates immunological memory.

The vaccines are produced in dry form, complete with a solvent, do not contain preservatives or antibiotics, and are stored at a temperature of 2 to 8°.

Mencevax ACWY. Young children traveling to an endemic zone are vaccinated subcutaneously no later than 2 weeks before departure; children under 2 years of age are given the 2nd dose after 3 months. Children over 6 years of age and adults can be vaccinated before departure.

Immunity

Immunization with a polysaccharide vaccine leads to a rapid (from day 5 to day 14) increase in antibodies; immunity persists in children for at least 2 years; in adults, antibodies after vaccination persist for up to 10 years. Revaccination is carried out no earlier than after 3 years.

Conjugate vaccines are immunogenic in children over 2 months, adolescents and adults, they create a significantly more intense immune response in children and adolescents. In addition, unlike non-conjugate vaccines, they induce the development of immunological memory.

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Vaccination reactions and contraindications to meningococcal vaccination

Vaccination against meningococcal infection A and Meningo A+C are low reactogenic. Local reaction - soreness and hyperemia of the skin - is observed in 25% of vaccinated, less often subfebrile temperature appears with normalization in 24-36 hours. Mencevax ACWY rarely causes temperature within 1 day, locally - redness, soreness at the injection site.

Contraindications are common for inactivated vaccines. The risk for pregnant women has not been established; they are vaccinated only if there is a high risk of disease.

Post-exposure prophylaxis of meningococcal infection

It is recommended to administer normal human immunoglobulin once to children from the meningitis focus aged under 7 years no later than 7 days after contact in doses of 1.5 (for children under 2 years) and 3.0 ml (over 2 years). Carriers in the focus are given chemoprophylaxis with amoxicillin for 4 days, and in closed groups of adults - rifampicin at 0.3 g 2 times a day. Abroad, prophylaxis with rifampicin for 2 days is accepted for all children who have had close contact (5-10 mg/kg/day for children under 1 year, 10 mg/kg/day for children aged 1-12 years) or a single intramuscular dose of ceftriaxone.

Since secondary cases of meningitis occur within a few weeks, chemoprophylaxis is supplemented by vaccination within the first 5 days after exposure.

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