acids and essential elements such as iron and potassium. The fermentation does not use bovine or porcine products. The cellular outer membranes are extracted with the detergent deoxycholate, which kills the bacteria. Outer membrane vesicles are purified out of the culture medium by ultracentrifugation, stabilised by histidine and then adsorbed to aluminium hydroxide Al(OH)3 as an adjuvant. Purification is achieved by ultrafiltration/diafiltration. Impact Since its introduction in 2004 the vaccine has had a dramatic impact on the meningitis epidemic began in 1991. Between 2004 and 2006 New Zealand offered free MeNZB vaccination to anyone under the age of 20. Routine immunisation for babies and preschoolers continued until June 2008. The last phase of this programme, immunisation for people with a high medical risk, ended in March 2011. Reasons given for this halt of the programme include that the epidemic was coming to an end, and that immune protection given by the vaccine is only short-term. The primary analysis estimated MeNZB to have an effectiveness of 77% after 3 doses and a mean follow-up time of 3.2 years. As N. gonorrhoeae and N. meningitidis are closely related bacteria and have 80–90% homology in their genetic sequences some cross-protection by meningococcal vaccines against N. gonorrhoeae infections is plausible. A study published in 2017 showed that MeNZB vaccine provided a partial protection against Gonorrhea. The vaccine efficiency was calculated to be 31%. References External links New Zealand Ministry of Health immunisation information. Immunisation Advisory Centre, University of Auckland. Evidence based information on meningococcal disease and MeNZB vaccine. MeNZB information from vaccine manufacturer Chiron's website. News article: The Meningococcal Gold Rush – An untested and experimental vaccine New Zealand Ministry of Health response to article linked above Press release: Minister Misleads Kim Hill and Public on MeNZB(tm) Press release: Increased Vaccine Risk in Pre-Schoolers – Explain Response to press release linked above: Unethical anti-science scaremongering Press release: MeNZB(tm) Vaccination Campaign Starts Derailing News article: Officials praise meningococcal B vaccine coverage TV news item covering vaccination campaign Ruling on complaint about TV news item covering vaccination campaign (linked above) News article: Adverts inform parents on vaccine Press release: MeNZB Early Indications Graph Meningococcal vaccines Subunit vaccines