[Source: Eurosurveillance, full page: (LINK). Abstract, edited.]
Eurosurveillance, Volume 21, Issue 16, 21 April 2016 / Systematic Review
Concordance of interim and final estimates of influenza vaccine effectiveness: a systematic review
VK Leung 1 , BJ Cowling 2 , S Feng 2 , SG Sullivan 1 3
Author affiliations: 1. World Health Organization Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, Australia; 2. World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; 3. Fielding School of Public Health, University of California, Los Angeles, United States
Correspondence: Sheena Sullivan (firstname.lastname@example.org)
Citation style for this article: Leung VK, Cowling BJ, Feng S, Sullivan SG. Concordance of interim and final estimates of influenza vaccine effectiveness: a systematic review. Euro Surveill. 2016;21(16):pii=30202. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.16.30202
Received:10 September 2015; Accepted:25 January 2016
The World Health Organization’s Global Influenza Surveillance and Response System meets twice a year to generate a recommendation for the composition of the seasonal influenza vaccine. Interim vaccine effectiveness (VE) estimates provide a preliminary indication of influenza vaccine performance during the season and may be useful for decision making. We reviewed 17 pairs of studies reporting 33 pairs of interim and final estimates using the test-negative design to evaluate whether interim estimates can reliably predict final estimates. We examined features of the study design that may be correlated with interim estimates being substantially different from their final estimates and identified differences related to change in study period and concomitant changes in sample size, proportion vaccinated and proportion of cases. An absolute difference of no more than 10% between interim and final estimates was found for 18 of 33 reported pairs of estimates, including six of 12 pairs reporting VE against any influenza, six of 10 for influenza A(H1N1)pdm09, four of seven for influenza A(H3N2) and two of four for influenza B. While we identified inconsistencies in the methods, the similarities between interim and final estimates support the utility of generating and disseminating preliminary estimates of VE while virus circulation is ongoing.
Keywords: Research; Abstracts; Seasonal Influenza; Vaccines.