Open AccessEffectiveness of seasonal influenza vaccine in preventing medically attended influenza infection in E ngland and W ales during the 2010/2011 season: a primary care‐based cohort study
Author(s) -
Kafatos George,
Pebody Richard,
Andrews Nick,
Durnall Hayley,
Barley Michele,
Fleming Douglas
Publication year - 2013
Publication title -
influenza and other respiratory viruses
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.743
H-Index - 57
eISSN - 1750-2659
pISSN - 1750-2640
DOI - 10.1111/irv.12163
Subject(s) - medicine , cohort , influenza vaccine , cohort study , primary care , influenza like illness , influenza a virus , seasonal influenza , respiratory tract infections , virus , pediatrics , immunology , respiratory system , covid-19 , disease , infectious disease (medical specialty) , family medicine
Background Estimates of seasonal influenza vaccine effectiveness ( VE ) are affected by factors such as the strain of the current circulating influenza virus and characteristics of the host. Objective The objective of this study was to provide VE estimates for the 2010/2011 seasonal trivalent influenza vaccine ( TIV ) in preventing medically attended influenza in E ngland and W ales for the season 2010/2011. Methods A cohort study design was employed using electronic health records extracted from 104 GP practices in the R oyal C ollege of G eneral P ractitioners ( RCGP ) primary care sentinel network. Endpoints included influenza‐like illness ( ILI ), lower respiratory tract infection ( LTRI ) as well as PCR ‐confirmed influenza from patients swabbed from practices participating in a swabbing scheme. Adjustment was made for age, month, underlying chronic condition, region and number of consultations in the 12 months prior to the study period. In addition to the cohort analysis, a nested test‐negative case–control analysis ( TNCC ) was carried out using the swab‐negative results as controls. Results In the cohort analysis, VE against LRTI was −0·5% [95% CI : (−7·0%, 7·5%)], against ILI was 37·8% [95% CI : (32·3%, 43·0%)] and against PCR ‐confirmed influenza was 50·0% [95% CI :(25·9%, 65·6%)] for type A and 44·4% [95% CI : (10·1%, 65·6%)] for type B . Using the TNCC design, the type A VE was 56·5% [95% CI : (30·4%, 72·7%)] and for type B was 54·0% [95% CI : (21·0%, 73·3%)]. Conclusions This study shows that the 2010/2011 TIV provided moderate protection against the circulating influenza strains for the 2010/2011 season. It also suggests that VE against the less specific diagnosis of ILI can be found, but less specific endpoints such as LRTI are not useful.