Modeling the public health impact of different meningococcal vaccination strategies with 4CMenB and MenACWY versus the current toddler MenACWY National Immunization Program in Chile.

Plain Language Summary (PLS)What is the context?Invasive meningococcal disease (IMD) is a severe, sometimes fatal, unpredictable disease with highest rates in infants, young children, and adolescents. It is caused by different serogroups of Neisseria meningitidis bacteria. Most cases in Chile are due to meningococcal serogroups B (MenB) and W (MenW). Following a MenW IMD outbreak in 2012, vaccination was introduced, leading to the current National Immunization Program (NIP) in toddlers with quadrivalent meningococcal conjugate vaccine (MenACWY) (protecting against IMD caused by MenA, C, W, and Y).What is new?A disease model to predict the impact of vaccination strategies in the Chilean population compared six alternative strategies, using the multi-component MenB (4CMenB) vaccine for infants (protecting against MenB, with potential cross-protection against MenW and Y IMD) and/or the MenACWY vaccine for toddlers and/or adolescents.What is the impact?Results, compared to the NIP, show that: Strategy 1 (a program targeting only infants with 4CMenB) would reduce more MenB cases but fewer MenA, C, W and Y cases resulting in a lower reduction of total IMD cases in the long term; Strategy 3 (a program targeting only adolescents with MenACWY) would have a similar effect to the NIP in the short term but a far greater IMD reduction in the long term (as vaccinating this age group eventually reduces transmission to other age groups, reducing their risk of disease); all the other strategies targeted more than one age group, further reducing numbers of IMD cases compared with the NIP. The greatest benefits were seen with infant 4CMenB vaccination combined with toddler and adolescent MenACWY vaccination. Results can help policymakers determine the best IMD strategy to maximize the benefits of available meningococcal vaccines.