11. MENINGOCOCCAL VACCINES
Polysaccharide quadrivalent vaccines against N. meningitidis serogroups A, C, W135 and Y are used in South Africa. A bivalent vaccine comprising serogroups A and C only, is also available. The main recipients of the quadrivalent vaccine are Hajj pilgrims to Mecca.
The serogroup A component of polysaccharide vaccines is effective from 3 months of age and protection persists for about 3 years. Protection afforded by the serogroup C, W-135 and Y is of shorter duration and offers poor protection in children less than 18 months. Vaccines only provide adequate protection 10 to 14 days following vaccination. Protein conjugate vaccines are more effective than polysaccharide vaccines in children under 2 years of age and have activity against nasal carriage of meningococci.
The development of vaccines against serogroup B has faced many challenges. Serogroup B polysaccharide is poorly immunogenic, even when conjugated to a protein carrier. Although outer membrane vaccines show some promise, strain-specific differences in outer-membrane proteins suggest that these vaccines may still not provide protection against all serogroup B meningococci.
Recent W-135 epidemics in West Africa have led to the use of a trivalent A C W135 vaccine.
Following several serogroup C meningococcal outbreaks in the United Kingdom, a conjugate C vaccine has been introduced into the routine childhood immunization programme, resulting in a dramatic drop in meningococcal disease incidence, Serogroup C conjugates have also been used to control serogroup C epidemics, notably in Canada.
11.1 Recommendations for use of meningococcal vaccine in South Africa
11.1.1 Pre-exposure vaccination
This can be used to protect individuals at risk (e.g. travellers to areas in Africa where there are epidemics, the military, and pilgrims to the Meningitis belt and to Saudi Arabia). Travellers to areas affected by meningococcal outbreaks are advised to be vaccinated. Pilgrims to the Hajj and Ramadan Omra, and visitors to Saudi Arabia must obtain a quadrivalent vaccine (against A, C, Y, W135) at least ten days prior to their arrival in the country.
Individuals who are at risk of severe disease or may be at increased risk of occupational exposure should also be offered quadrivalent vaccine. This includes:
- persons with functional or anatomical asplenia
- individuals with terminal complement deficiencies
- laboratory staff in reference laboratories who routinely work with N. meningitidis
11.1.2 Pre-exposure vaccination for university students and boar ding schools
Vaccination is not currently routinely recommended for 1st year students moving into university residences in SA. However, students and their parents should be informed of the existing very small risk, which could be decreased through vaccination. The disease incidence rate for incoming students into residences compared to the general population in the US in 1999 was 4.6/100 000 compared to 1.7/100 000 person years. Currently there are no local SA data to quantify this risk.
11.1.3 Post exposur e vaccination
Close contacts of cases that have been given chemoprophylaxis can later be offered appropriate vaccine once the serogroup has been confirmed. This will extend the period of protection. Vaccine can be given up to 4 weeks after exposure as a preventive measure for close contacts; it does not have to be given as an urgent procedure. Use of vaccine does NOT replace the immediate need for chemoprophylaxis in close contacts as the serogroup will be unknown and vaccine does not offer immediate protection.