old received a single dose of the vaccine in December 2011. Vaccinating 70% of the population in that age group is enough to create "herd immunity". 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 decrease 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. In November 2015, a special collection of 29 articles was published in the journal Clinical Infectious Diseases—with guest editors from Public Health England and the former Meningitis Vaccine Project about the steps taken for the development, introduction, and evaluation of MenAfriVac. Immunization with MenAfriVac has led to the control and near elimination of deadly meningitis A disease in the African "meningitis belt". In 2013, only four laboratory-confirmed cases of meningitis A were reported by the 26 countries in the meningitis belt. But scientists warned that unless countries within the belt incorporate the meningitis A vaccine in routine immunization schedules for infants, there is a risk that the disease could rebound in 15 years' time. One of the journal studies found that a childhood vaccination strategy will be much cheaper than reacting to future epidemics with disruptive and costly case management and mass vaccination campaigns. 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. 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. 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