title: Descriptive investigation of the recording of influenza vaccination details on The Health Information Network database.
abstract: BACKGROUND
  The UK primary care databases are used in pharmacoepidemiology studies of vaccination type. We investigated vaccine recording and whether, and how, exposure to specific brands and batches can be identified.
  
  
  METHODS
  Details of influenza vaccinations given in the 2010-2011 or 2011-2012 seasons were identified from coded and text fields in The Health Information Network UK primary care database. The proportion of people over 64 years of age vaccinated against influenza was compared with published regional rates. Searches for Fluvirin (Novartis Vaccines and Diagnostics GmbH, Marburg, Germany) batch numbers and name identified exposure to this specific vaccine. The recording of any brand name and batch number was described for a sample of 1000 vaccinations across 472 practices.
  
  
  RESULTS
  A total of 767 904 influenza vaccinations were identified during the 2010-2011 season and 784 518 in 2011-2012. Vaccination rates for people aged over 64 years were 75.6%, 80.9%, 78.4% and 71.9% in England, Northern Ireland, Scotland and Wales, respectively (2011-2012 season), compared with published figures of 74.0%, 77.0%, 76.2% and 67.7%. Rates were slightly lower in 2010-2011 in both data sources. A Fluvirin brand was identified for 3.6% of all UK vaccinations but 26.2% of those in Scottish practices. Vaccination brand could be identified for 94.3% of the sample, 93.6% with a batch number. Batch number (98.5%) and brand name (50.3%) were most frequently recorded in an immunisation 'batch' text field.
  
  
  CONCLUSIONS
  Patients exposed to an influenza vaccine in primary care can be identified from The Health Information Network. Identification of brand or batch number requires a text search. Regional variation in brand of vaccine should be considered when estimating sample size.
authors.affiliation: Grimsdyke House, London, UK.
authors.forename: Gillian C
authors.initials: GC
authors.lastname: Hall
authors.forename: Fiona
authors.initials: F
authors.lastname: Hill
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D016208:Databases, Factual / Q000592:standards / Q000706:statistics & numerical data; D057286:Electronic Health Records / Q000592:standards / Q000706:statistics & numerical data; D007252:Influenza Vaccines / Q000627:therapeutic use; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control; D007255:Information Services / Q000592:standards; D006113:United Kingdom; D014611:Vaccination / Q000592:standards / Q000706:statistics & numerical data
chemical_list: D007252:Influenza Vaccines
keywords: batch number; influenza; pharmacoepidemiology; primary care database; vaccination; validation