Using the impact of pneumococcal vaccines on nasopharyngeal carriage to aid licensing and vaccine implementation; A Pneumocarr meeting report March 27-28, 2012, Geneva

An international consultation was convened in March 2012 to provide feedback on the Case for Carriage, a summary statement by the Pneumococcal Carriage Consortium (PneumoCarr) proposing nasopharyngeal (NP) colonization as a supplementary or alternative endpoint in vaccine licensure. PneumoCarr members provided information to vaccine manufacturers, regulators and the WHO on the evidence for NP carriage as a precursor to pneumococcal disease, standardization of laboratory methods for the detection of multiple serotype carriage, definition and estimation of pneumococcal vaccine efficacy against carriage (VE-col), and the direct and indirect impact of vaccination on carriage. Manufacturers and regulators had the opportunity to respond to the information compiled by PneumoCarr and share their perspectives. VE-col as a licensure endpoint may be more useful for the next generation pneumococcal vaccine products, particularly those for which the immunological correlate of protection is not established, whereas it may be less needed for pneumococcal conjugate vaccines which have an established licensure pathway. The consultation supported the importance of NP carriage data as a critical element linking vaccine impact on the individual direct risk of disease to the population-level impact: indirect effects such as herd protection and serotype replacement. The indirect effects of vaccination, however, are not currently established as part of the licensure process and to include them would be a paradigm shift for regulatory agencies who currently consider this information in the post-licensure setting. More discussion and consensus-building is needed around the rationale and optimal mechanism to include carriage data in the licensure pathway for new pneumococcal vaccines. The WHO and national advisory groups on immunization policy may have an important role in considering the evidence for the indirect benefit of vaccination as informed by its impact on NP carriage.