@article{17eeb130252f438f858a74ae89dd62a6,
title = "Intraseason decline in influenza vaccine effectiveness during the 2016 southern hemisphere influenza season: A test-negative design study and phylogenetic assessment",
abstract = "Background: We estimated the effectiveness of seasonal inactivated influenza vaccine and the potential influence of timing of immunization on vaccine effectiveness (VE) using data from the 2016 southern hemisphere influenza season. Methods: Data were pooled from three routine syndromic sentinel surveillance systems in general practices in Australia. Each system routinely collected specimens for influenza testing from patients presenting with influenza-like illness. Next generation sequencing was used to characterize viruses. Using a test-negative design, VE was estimated based on the odds of vaccination among influenza-positive cases as compared to influenza-negative controls. Subgroup analyses were used to estimate VE by type, subtype and lineage, as well as age group and time between vaccination and symptom onset. Results: A total of 1085 patients tested for influenza in 2016 were included in the analysis, of whom 447 (41%) tested positive for influenza. The majority of detections were influenza A/H3N2 (74%). One-third (31%) of patients received the 2016 southern hemisphere formulation influenza vaccine. Overall, VE was estimated at 40% (95% CI: 18–56%). VE estimates were highest for patients immunized within two months prior to symptom onset (VE: 60%; 95% CI: 26–78%) and lowest for patients immunized >4 months prior to symptom onset (VE: 19%; 95% CI: −73–62%). Discussion: Overall, the 2016 influenza vaccine showed good protection against laboratory-confirmed infection among general practice patients. Results by duration of vaccination suggest a significant decline in effectiveness during the 2016 influenza season, indicating immunization close to influenza season offered optimal protection.",
keywords = "Case-control study, Influenza, Influenza vaccines, Test-negative design, Vaccine effectiveness",
author = "Regan, {Annette K.} and Fielding, {James E.} and Chilver, {Monique B.} and Carville, {Kylie S.} and Minney-Smith, {Cara A.} and Grant, {Kristina A.} and Chloe Thomson and Trish Hahesy and Deng, {Yi Mo} and Nigel Stocks and Sullivan, {Sheena G.}",
note = "Funding Information: We thank the general practitioners, nurse practitioners, and practice staff that participated and contributed to ASPREN, VicSPIN and SPNWA in 2016. We also thank laboratory staff members from the following laboratories who undertook influenza testing and virus characterisation: SA Pathology, Adelaide, South Australia; the Victorian Infectious Diseases Reference Laboratory, Melbourne, Victoria; PathWest Laboratory Medicine, Perth, Western Australia; and the WHO Collaborating Centre for Reference and Research on Influenza, Melbourne, Victoria. The Australian Sentinel Practices Research Network and the WHO Collaborating Centre for Reference and Research on Influenza are supported by the Australian Government Department of Health (the Department). The opinions expressed in this paper are those of the authors, and do not necessarily represent the views of the Department. The Victorian Sentinel Practice Influenza Network is supported by the Victorian Government Department of Health and Human Services. The WA Sentinel Practices Network is supported by the Western Australian Government Department of Health. AKR was supported by a NHMRC Early Career Fellowship (GNT1138425). The funding sources had no role in the study design, analysis of data, or decision to submit the article for publication. The authors have no potential conflicts of interest to disclose. Funding Information: The Australian Sentinel Practices Research Network and the WHO Collaborating Centre for Reference and Research on Influenza are supported by the Australian Government Department of Health (the Department). The opinions expressed in this paper are those of the authors, and do not necessarily represent the views of the Department. The Victorian Sentinel Practice Influenza Network is supported by the Victorian Government Department of Health and Human Services. The WA Sentinel Practices Network is supported by the Western Australian Government Department of Health. AKR was supported by a NHMRC Early Career Fellowship (GNT1138425). Publisher Copyright: {\textcopyright} 2019",
year = "2019",
month = may,
day = "1",
doi = "10.1016/j.vaccine.2019.02.027",
language = "English",
volume = "37",
pages = "2634--2641",
journal = "Vaccine",
issn = "0264-410X",
publisher = "Elsevier",
number = "19",
}
