Meningococcal vaccine

Abstract

Meningococcal meningitis is caused by Neisseria meningitidis, a gram-negative, aerobic, encapsulated diplococcus. Meningococci are divided into numerous serogroups based on the composition of their capsular polysaccharide (Ps) antigens. At least 13 serogroups have been described: A, B, C, D, 29E, H, I, K, L, W-135, X, Y and Z. Out of these 13, six (A, B, C, W135, X and Y) can cause epidemics. The incubation period averages 3–4 d (range 1–10 d), which is the period of communicability. Bacteria can be found for 2–4 d in the nose and pharynx, and for up to 24 h after starting antibiotics. N. meningitidis is a leading cause of meningitis worldwide and a significant public health problem and dreaded disease in most countries. Morbidity and mortality rates from the disease remain high. Apart from epidemics, at least 1.2 million cases of bacterial meningitis are estimated to occur every year, 135,000 of which are fatal – of these, ~500,000 and ~50,000 respectively are caused by meningococci. Many outbreaks of meningococcal meningitis have been documented, with major outbreaks mainly seen in large cities of northern, western and eastern India like New Delhi, Mumbai, Kolkata and northeastern states. In 2011, 245 people died in India, the vast majority (179) in West Bengal, while 467 and 341 people in 2009 and 2010 respectively died of this disease. The meningococcal conjugate vaccines (MCV) are preferred for reasons of immunogenicity and persistence of immunity but are unavailable in India. Only the quadrivalent and bivalent meningococcal Ps vaccines (MPV) are available in India. The quadrivalent MPV is preferred for Haj pilgrims, international travelers and students in that it provides protection against emerging W-135 and Y disease in these areas. A single-dose 0.5mL injection is recommended.