MenAfriVac
MenAfriVac is a vaccine developed for use in sub-Saharan Africa that protects infants under one year old to people up to 29 years of age against meningococcal bacterium Neisseria meningitidis group A. MenAfriVac costs under US$0.50 per dose and reduces transmission of the bacteria between people.[1][2][3][4] The Meningitis Vaccine Project, a partnership between the Program for Appropriate Technology in Health (PATH) and the World Health Organization, worked with a consortium of international partners to develop the vaccine.[5]
Contents
History
The largest meningitis epidemic in African history swept across sub-Saharan Africa from 1996 to 1997, numbering 250,000 new cases and taking 25,000 lives. Three years later, the World Health Organization (WHO) held a technical consultation in Cairo, Egypt with African ministers of health and global health leaders to discuss meningitis and the development of a new vaccine. At that meeting, representatives from eight African countries issued a statement saying that the development of a meningococcal vaccine to prevent epidemics was a high priority for them, and concluded that a conjugate meningococcal vaccine would have the potential to prevent future epidemics. They estimated that the new vaccine could become available in three to seven years for US$ 0.40 to $ 1 a dose, providing protection for at least ten years.[6]
A year later, in 2001, the Bill & Melinda Gates Foundation provided a ten-year, $70 million grant to establish the Meningitis Vaccine Project, a partnership between PATH and WHO. The foundation charged the new project with development, testing, licensure and mass introduction of a meningococcal conjugate vaccine.[7] In 2002, the collaboration supported reinforced meningitis surveillance activities in 12 countries in Africa: Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Côte d’Ivoire, Ethiopia, Ghana, Mali, Niger, Nigeria and Togo. The surveillance indicated an increased risk of outbreaks in the future and the continued need for a vaccine.[8] MenAfriVac became available for widespread use in African meningitis belt countries in 2010.[5]
Effectiveness evaluation
A 2013 article published in The Lancet, reported that the MenAfriVac vaccination campaign in Chad reduced meningitis incidence by 94%. In three regions of Chad, approximately 1.8 million people from one to 29 years old received a single dose of the vaccine in December 2011.[9][10] Vaccinating the 70% of the population in that age group is enough to create "herd immunity".[11] During the 2012 meningitis season no cases of the meningococcus sub-type serogroup A caused disease in places where mass vaccination took place. Carriers of serogroup A were found to reduce by more than 97% post vaccination. Surveillance is needed to continue for several more years to establish the length of effective period of the vaccine and whether other meningococci serogroups may surge to replace serogroup A.[9][10]
Eradication
In 2015, the caseload of the illness fell to zero in 16 countries that used MenAfriVac in mass vaccination campaigns. Ten other countries have not launched vaccination programs. Epidemics were expected to return in about 15 years unless MenAfriVac becomes a routine childhood vaccination as WHO recommended.[11]
The tetanus toxoid protein used in the vaccine increased the share of people with long-term tetanus immunity from 20% to 59%, although it is not strong enough to stand alone against tetanus. Neonatal tetanus kills nearly 50,000 newborns a year in sub-Saharan Africa. Rates of neonatal tetanus fell by 25% in countries following a MenAfriVac campaign.[11]
Manufacture
The Meningitis Vaccine Project partnered with SynCo Bio Partners, a Dutch biotech company, and the US government’s Center for Biologics Evaluation and Research to develop MenAfriVac, and the Serum Institute of India to manufacture it.
MenAfriVac is a freeze-dried vaccine of a polysaccharide from a type of Neisseria meningitidis called group A. The polysaccharide has been purified by affinity chromatography and bound to a carrier protein called tetanus toxoid. The TT is prepared by extraction by ammonium sulfate precipitation and the toxin is inactivated with formalin from cultures of Clostridium tetani grown in a modified Mueller-Hinton agar.[12]
References
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