Evaluation of influenza vaccine effectiveness - A guide to the design and interpretation of observational studies

Overview

The guide is organized in the following sections:
Section 2 describes the role of influenza VE studies in implementing and evaluating influenza vaccination programmes.
Sections 3–5 cover outcomes of interest, measuring vaccination history, and measuring potential confounders – topics of importance for any influenza VE study.
Section 6 reviews different designs that could be used for influenza VE studies, and the strengths and limitations of each.
Section 7 reviews statistical considerations for designing VE studies and for analysing VE study data.
Section 8 provides a more detailed description of one specific design that is most likely to be attempted in low-resource settings where influenza vaccines have been introduced to at least some parts of the population: a test-negative study built on an existing severe acute respiratory infection (SARI) surveillance system.
Section 9 describes key elements that need to be included in any report of an influenza VE study, so that the results can be properly interpreted.