title: Validating child vaccination status in a demographic surveillance system using data from a clinical cohort study: evidence from rural South Africa.
abstract: BACKGROUND
  Childhood vaccination coverage can be estimated from a range of sources. This study aims to validate vaccination data from a longitudinal population-based demographic surveillance system (DSS) against data from a clinical cohort study.
  
  
  METHODS
  The sample includes 821 children in the Vertical Transmission cohort Study (VTS), who were born between December 2001 and April 2005, and were matched to the Africa Centre DSS, in northern KwaZulu-Natal. Vaccination information in the surveillance was collected retrospectively, using standardized questionnaires during bi-annual household visits, when the child was 12 to 23 months of age. DSS vaccination information was based on extraction from a vaccination card or, if the card was not available, on maternal recall. In the VTS, vaccination data was collected at scheduled maternal and child clinic visits when a study nurse administered child vaccinations. We estimated the sensitivity of the surveillance in detecting vaccinations conducted as part of the VTS during these clinic visits.
  
  
  RESULTS
  Vaccination data in matched children in the DSS was based on the vaccination card in about two-thirds of the cases and on maternal recall in about one-third. The sensitivity of the vaccination variables in the surveillance was high for all vaccines based on either information from a South African Road-to-Health (RTH) card (0.94-0.97) or maternal recall (0.94-0.98). Addition of maternal recall to the RTH card information had little effect on the sensitivity of the surveillance variable (0.95-0.97). The estimates of sensitivity did not vary significantly, when we stratified the analyses by maternal antenatal HIV status. Addition of maternal recall of vaccination status of the child to the RTH card information significantly increased the proportion of children known to be vaccinated across all vaccines in the DSS.
  
  
  CONCLUSIONS
  Maternal recall performs well in identifying vaccinated children aged 12-23 months (both in HIV-infected and HIV-uninfected mothers), with sensitivity similar to information extracted from vaccination cards. Information based on both maternal recall and vaccination cards should be used if the aim is to use surveillance data to identify children who received a vaccination.
authors: Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Mtubatuba, South Africa. jndirangu@africacentre.ac.za
authors: James
authors: J
authors: Ndirangu
authors: Ruth
authors: R
authors: Bland
authors: Till
authors: T
authors: Bärnighausen
authors: Marie-Louise
authors: ML
authors: Newell
references: N Engl J Med. 2006 Aug 3;355(5):447-55
references: 16885548
references: Vaccine. 2011 Mar 16;29(13):2371-80
references: 21159324
references: Trop Med Int Health. 2009 Nov;14(11):1383-93
references: 19737375
references: Lancet. 2002 May 4;359(9317):1564-8
references: 12047966
references: Lancet. 2005 Sep 3-9;366(9488):832-9
references: 16139658
references: J Infect Dis. 2004 Aug 1;190(3):477-83
references: 15243919
references: BMC Public Health. 2007 Jul 18;7:160
references: 17640354
references: Lancet. 2007 Mar 31;369(9567):1107-16
references: 17398310
references: AIDS. 2007 Nov;21 Suppl 6:S87-96
references: 18032944
references: Bull World Health Organ. 2009 Oct;87(10):754-62
references: 19876542
references: Lancet. 2007 Apr 14;369(9569):1277-1285
references: 17434403
references: Lancet. 2010 Jul 17;376(9736):160
references: 20638558
references: Acta Paediatr. 1998 Apr;87(4):458-9
references: 9628307
references: Lancet. 2004 Dec 18-31;364(9452):2204-11
references: 15610807
references: Int J Epidemiol. 2010 Apr;39(2):351-60
references: 19336438
references: Trop Med Int Health. 2001 Oct;6(10):826-38
references: 11679131
references: BMC Int Health Hum Rights. 2009 Oct 14;9 Suppl 1:S13
references: 19828057
references: S Afr Med J. 2008 Nov;98(11):842, 844-6
references: 19177886
references: Vaccine. 2007 Jan 8;25(4):664-71
references: 17049682
references: Int J Epidemiol. 2009 Aug;38(4):1008-16
references: 19261659
references: AIDS Care. 2006 Oct;18(7):755-63
references: 16971285
references: AIDS Res Hum Retroviruses. 2009 Apr;25(4):405-9
references: 19320571
references: Int J Epidemiol. 2008 Oct;37(5):956-62
references: 17998242
references: J Manag Care Pharm. 2007 Sep;13(7 Suppl B):S12-5
references: 17955624