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COVER Methods

Methods of collection and publication of data for the COVER programme

Methods of data collection

Quarterly UK COVER reports
Computerised child health information systems provide information for children reaching their first, second, or fifth birthdays during a particular evaluation quarter. In England the health service administration for which data were requested was the Health Authority (HA) up to the evaluation quarter beginning 1st January 2003, and subsequently the responsible Primary Care Trust/Organisation (PCT/PCO). Data are also provided for the Health Boards (HBs) Scotland (15) and Northern Ireland (4), and Administrative Regions in Wales (3). In England, the PCT/PCOs and GORs (Government Office Regions) have different boundaries and populations to health authorities and regional health authorities used in quarterly reports before April 2003. The PCT/PCO responsible population for COVER data includes all children registered with a general practitioner whose practice forms part of the PCT/PCO, regardless of where the child is resident. In addition, the PCT/PCO responsible population will also include any children not registered with a general practitioner (GP), who are resident within the PCT/PCOs statutory geographical boundary. Children resident within the PCT/PCO geographical area, but registered with a GP belonging to another PCT/PCO, are the responsibility of that other PCT/PCO. The number of Strategic Health Authorities (SHAs) in England was reduced from 28 to 10 on 1 July 2006, and the number of PCTs in England was reduced from 303 to 152 on 1 October 2006.

Details of SHAs and PCTs [external link].

Annual UK COVER reports
PCT/PCO data were first requested for annual submissions for the fiscal year 2002/3. HA and PCT/PCO data are aggregated to Strategic Health Authority (SHA), and Government Office Regions (GORs), HB data to devolved administrations/country, and to UK levels. COVER annual reports examine trends at the level of the devolved administrations and the UK with some further breakdown to HB and PCT/PCO level for the purposes of GIS mapping.

Information about COVER data returns, including data definitions, are covered by Data Set Change Notices.

There are three data collections within the COVER programme:

  1. UK Primary and pre-school booster vaccinations data
  2. Neonatal hepatitis B vaccine coverage data in England
  3. MMR sentinel surveillance scheme coverage in England

UK Primary and pre-school booster vaccinations data

COVER data are extracted from Child Health Information Systems (CHISs) on a quarterly and annual timetable.

Data are submitted to the HPA Centre for Infections (CfI) in the second and third months following the end of the appropriate evaluation quarter for children resident in Administrative Regions in Wales, Health Boards in Scotland and Northern Ireland, and for children in the Primary Care Trust (PCT) responsible population (as defined above) in England, on the last day of the evaluation quarter.

Coverage data for each demographic level (UK, country, region, local) are collected for all routine vaccinations offered according to the current immunisation schedule.

Neonatal hepatitis B vaccine coverage data in England

Following the introduction of universal antenatal testing for hepatitis B in April 2001, HPA Centre for Infections has been attempting to collate coverage data on infants born to hepatitis B positive mothers at their first and second birthdays. Since April 2005, this data collection has become a statutory NHS data return and been integrated into the routine COVER programme. The data represent coverage of three doses of hepatitis B vaccine, given at any time up to their first birthday, in those infants born to HBsAg positive mothers who reached the age of one year in the appropriate evaluation quarter, and coverage of four doses of hepatitis B vaccine, given at any time up to their second birthday, in infants who reached two years of age. Data may be extracted from CHISs, manual systems, or from standalone databases managed by or behalf of the local immunisation co-ordinator.

1. Although many child health systems do not have the capacity to produce statistics or even hold information on hepatitis B vaccines, this information is requested in the same format as the current COVER outputs. This is designed to ensure that collection of hepatitis B data is integrated into the routine collection and coverage data can be compared. It is hoped that this data will be generated from manual systems or from standalone databases managed by or on behalf of the local immunisation co-ordinator.

2. The format is based on the 0, 1, 2, 12 month schedules recommended in the Health Service Circular (HSC) 1998/127.
3. The HSC recommended universal screening of pregnant women from April 2000. Data on antenatal prevalence will be collected at regional level and can be used to validate the completeness of identification of children at risk in future cohorts.
4. The COVER programme aims only to collate information on completion of vaccination, although it is acknowledged that first dose coverage and timeliness may be more important in the prevention of infection.

MMR sentinel surveillance scheme coverage in England

In order to give a more timely indication of trends in MMR coverage, a sentinel surveillance scheme has monitored MMR coverage in a sample of children becoming 16 and 24 months of age in a particular month in England from April 1999. Initially, this information was requested every four months for all children who were turning 16 months or 24 months of age in the defined one month period and living in the participating trusts'/health authorities' area. From March 2001, the request was made quarterly so that the information coincided with routine COVER reports. Since March 2002, this information has been routinely collected every month. The request was extended in June 2002 to include coverage at 20 and 36 months of age to determine whether there is further improvement in coverage as children get older, because some parents delay MMR vaccination (rather than refuse). This sentinel scheme is based on a sample of trusts/PCTs in England and represents approximately 20% of the population, although monthly reporting is not always complete for the whole sample. This means that these data are not geographically representative or sufficiently detailed to allow comparison between regions, and will be subject to greater variability than the national data due to varying monthly sample size.

Vaccine coverage targets

These data are evaluated against the World Health Organization (WHO) targets of 95% coverage annually for each antigen (except MenC) by two years of age at the national level and of at least 90% coverage annually in each strategic health authority ( WHO Regional Office for Europe. Operational targets for EPI diseases. 1996. EUR/ICP/CMDS 01 01 11 Rev.1)