MenAfriVac

MenAfriVac is a vaccine developed for use in sub-Saharan Africa for children and adults between 9 months and 29 years of age against meningococcal bacterium Neisseria meningitidis group A. The vaccine costs less than US$0.50 per dose.[1][2]

History

Epidemics of meningococcal A meningitis, which is a bacterial infection of the thin lining surrounding the brain and spinal cord, have swept across 26 countries in sub-Saharan Africa for a century, killing and disabling young people every year. The disease is highly feared on the continent; it can kill or cause severe brain damage in a child within hours. Epidemics usually start at the beginning of the calendar year when dry sands from the Sahara Desert begin blowing southward.

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.[3]

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.[4]

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.[5] MenAfriVac became available for widespread use in African meningitis belt countries in 2010.[6]

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.[7][8] Vaccinating the 70% of the population in that age group is enough to create "herd immunity".[9] 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.[7][8]

In November 2015, special collection of 29 articles in the journal Clinical Infectious Diseases—with guest editors from Public Health England and the former Meningitis Vaccine Project, a partnership between the World Health Organization (WHO) and the international health nonprofit PATH—about the steps taken for the development, introduction, and evaluation of MenAfriVac.[10] 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 are now warning 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.[9]

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.[9]

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.[11]

References
  1. World Health Organization (November 2011). "Meningococcal vaccines. World Health Organization position paper, November 2011" (PDF). World Health Organization. Retrieved 31 January 2017.
  2. World Health Organization (February 2015). "Meningococcal A conjugate vaccine: updated guidance. World Health Organization" (PDF). World Health Organization. Retrieved 31 January 2017.
  3. "Improved meningitis vaccine for Africa could signal eventual end to deadly scourge". 8 June 2007. World Health Organization. Retrieved 24 November 2010.
  4. "The Bill & Melinda Gates Foundation Announces Grant for the Elimination of Epidemic Meningitis in Sub-Saharan Africa". May 30, 2001. Bill & Melinda Gates Foundation. Retrieved 24 November 2010.
  5. "WHO weekly epidemiology record" (PDF). September 16. 2005. World Health Organization. Retrieved 24 November 2010.
  6. Anderson, Tatum (14 October 2010). "Africa hails new meningitis vaccine". 14 October 2010. BBC News. Retrieved 24 November 2010.
  7. Press Release (12 September 2013). "Vaccine campaign in sub-Saharan Africa reduces meningitis by 94 per cent". Wellcome Trust. Retrieved 13 September 2013.
  8. Greenwood, BM; Daugla, DM; Gami, JP; Gamougam, K; Naibei, N; MBainadji, L; Narbe, M; Toralta, J; et al. (12 September 2013). "Effect of a serogroup A meningococcal conjugate vaccine (PsA-TT) on serogroup A meningococcal meningitis and carriage in Chad: a community trial". The Lancet. 383 (9911): 40–47. doi:10.1016/S0140-6736(13)61612-8. PMC 3898950. PMID 24035220.
  9. "Knockout jab". The Economist. November 14, 2015. ISSN 0013-0613. Retrieved 2015-11-23.
  10. "The Meningitis Vaccine Project: The Development, Licensure, Introduction, and Impact of a New Group A Meningococcal Conjugate Vaccine for Africa". Clinical Infectious Diseases. 61 (suppl_5): 673.1–673. 2016. doi:10.1093/cid/civ1186.
  11. "MenAfriVac Meningococcal A Conjugate Vaccine". seruminstitute.com. Serum Institute of India. 2011. Retrieved 17 June 2011.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.