Dr Caroline Trotter and her team at Cambridge’s Department of Veterinary Medicine have used mathematical modelling to help ensure that World Health Organisation guidelines provide the most robust and effective approach to meningitis vaccinations.

Meningitis is a devastating infection that causes the swelling of the meninges, the membranes surrounding the brain and spinal cord. It can lead to brain damage and deafness, as well as fatalities.  The land mass stretching from Senegal to Ethiopia is known as the “meningitis belt” and during the past 100 years has suffered epidemics that have killed thousands and disabled even more, the bulk of victims being children and youth.  Between 1996 and 1997 an epidemic of meningitis A resulted in 250,000 cases and took over 25,000 lives.  Thankfully, in 2010, the MenAfriVac® vaccine was introduced. With over 235 million people immunised so far, the caseload of meningitis A has been eliminated in immunised populations.

However, Dr Trotter’s research assistant Andromachi Karachaliou and her colleagues showed that without a long-term vaccination programme, meningitis A would return to the region within 15 years.  The team used mathematical modelling to examine the most effective vaccination strategy to ensure the population was protected in the long term,  which informed World Health Organisation (WHO) recommendations. The success of the MenAfriVac® also changed the makeup of the meningitis threat, which prompted WHO to commission Dr Trotter to review operational thresholds for other serogroups of meningitis, which dictate timelines to act to prevent or to respond to epidemics.  Dr Trotter analysed district-level surveillance data to show that initiating vaccination programmes earlier would prevent more cases of meningitis than would lowering the epidemic threshold, which led WHO to lower the alert thresholds, thus allowing more time to prepare for a rapid response once the epidemic threshold was reached.

To read the case study in full, visit the Cambridge Institute of Public Health website at http://www.iph.cam.ac.uk/public-health-policy/case-studies/shaping-vaccination-guidelines