Vaccine
Volume 32, Issue 26, Pages 3115-3340 (30 May 2014)
http://www.sciencedirect.com/science/journal/0264410X/32

Vaccine preventable disease incidence as a complement to vaccine efficacy for setting vaccine policy
Review Article
Pages 3133-3138
Bradford D. Gessner, Daniel R. Feikin
Abstract
Traditionally, vaccines have been evaluated in clinical trials that establish vaccine efficacy (VE) against etiology-confirmed disease outcomes, a measure important for licensure. Yet, VE does not reflect a vaccine’s public health impact because it does not account for relative disease incidence. An additional measure that more directly establishes a vaccine’s public health value is the vaccine preventable disease incidence (VPDI), which is the incidence of disease preventable by vaccine in a given context. We describe how VE and VPDI can vary, sometimes in inverse directions, across disease outcomes and vaccinated populations. We provide examples of how VPDI can be used to reveal the relative public health impact of vaccines in developing countries, which can be masked by focus on VE alone. We recommend that VPDI be incorporated along with VE into the analytic plans of vaccine trials, as well as decisions by funders, ministries of health, and regulatory authorities.