Situation update on meningitis C epidemic risk
21 December 2017 - As bacterial meningitis season begins in West Africa this year, a convergence of factors is threatening the region with large outbreaks affecting millions. A new hyper-invasive strain of meningococcal meningitis serogroup C is circulating at the same time that an acute shortage of meningitis C-containing vaccine threatens to severely limit the region’s ability to minimize the number of persons affected. The risk of imminent large-scale epidemics is dangerously high. Last year alone, the Nm C strain caused 18,000 cases in Nigeria and Niger. Attack rates can be very high (up to 670 cases/100,000), population immunity is low, the strain is already circulating in neighboring countries of the African meningitis belt (Burkina Faso, Mali) and it showed a potential to spread outside the belt as observed in Liberia.
Meningitis is a severe disease that can cause 20,000 to 200,000 cases in large-scale outbreaks. Those affected die in 10% of cases, and those who survive are at risk of severe neurological consequences. Epidemics of meningococcal meningitis hit the African meningitis belt in periodic waves and are frequently associated with the spread of new epidemic strains. Of the 6 serogroups (A, B, C, W, X and Y) known to cause epidemics, serogroup A was responsible for the most devastating large-scale outbreaks in this region. However, since the successful roll-out of the Men A conjugate vaccine since 2010, cases of serogroup A have fallen by 99%.
The new serogroup C strain now represents the major risk of meningitis outbreaks in the region. According to WHO estimates validated by international meningitis experts, the worst-case expansion scenario could result in as many as 70,000 cases in the next two years.
Urgent action is needed to prepare for the worst and minimize the potentially devastating impact of outbreaks in the region. But stocks of C-containing vaccine are alarmingly inadequate WHO calls on technical and operational partners, vaccine manufacturers, and donors to act now to increase the availability of meningococcal vaccines that protect against serogroup C. The 2018 emergency international stockpile has just 2.5 million doses of C containing vaccine. The immediate need is for an additional 10 million doses to complement the current stockpile for 2018-2019. The priority is for conjugate vaccines. Despite the high cost, they offer the best prospects for disease control by offering a long-lasting immune response.
Meningitis epidemics in the African meningitis belt constitute an enormous public health burden. Shortages of vaccine to control the new hyper-invasive strain portend a catastrophe with potential to affect as many as 34 million persons in the region. By raising the alert now, WHO hopes to close the critical vaccine gap and keep this highly feared disease from sweeping across and potentially beyond West Africa.