Meningococcal vaccines and herd immunity: lessons learned from serogroup C conjugate vaccination programs

Abstract

Effective vaccines provide direct protection to immunized individuals, but may also provide benefits to unvaccinated individuals by reducing transmission and thereby lowering the risk of infection. Such herd immunity effects have been demonstrated following the introduction of meningococcal serogroup C conjugate (MCC) vaccines, with reductions in disease attack rates in unimmunized individuals and significantly lower serogroup C carriage attributable to the vaccine introduction. In the UK, targeting teenagers for immunization was crucial in maximizing indirect effects, as most meningococcal transmission occurs in this age group. Questions remain regarding the duration of herd protection and the most appropriate long-term immunization strategies. The magnitude of the herd effects following MCC vaccination was largely unanticipated, and has important consequences for the design and evaluation of new meningococcal vaccines.

Keywords::

• conjugate vaccine
• epidemiology
• herd immunity
• immunization
• meningococcal carriage
• meningococcal vaccine
• Neisseria meningitidis

Financial & competing interests disclosure

Caroline Trotter is supported by a Personal Award Scheme Post-Doctoral Award from the National Institute of Health Research (Department of Health, UK). Martin Maiden is a Wellcome Trust Senior Research Fellow in Basic Biomedical Sciences. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.