Appendix 2. Further detail on methods
Published 5 March 2026
Applies to England
© Crown copyright 2026
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Review of routinely collected vaccination coverage data
The 3 main data sources for vaccination coverage in England were reviewed – the cover of vaccination evaluated rapidly programme (COVER), Immform and the immunisation information system (ISS).
COVER
The cover of vaccination evaluated rapidly programme (COVER) evaluates childhood immunisation in England, with data available for children aged 1, 2 and 5 years. Data is primarily sourced from Child Health Information Systems (CHIS), local systems that record immunisation and health records of children, and submitted to the NHS England Strategic Data Collection Service. The UK Health Security Agency (UKHSA) collects this data from NHS England to compile national statistics.
ImmForm
ImmForm is an UKHSA website used to both collect data on vaccine uptake and provide ordering facilities for vaccines used in the NIP. This data includes anonymous, aggregated information on vaccine uptake rates from various surveys and programmes. GPs and other healthcare providers enter vaccine data directly into the ImmForm website via survey forms or using automated platforms.
IIS
The immunisation information system (IIS) is an individual-level vaccine and eligible population record system, containing around 68 million primary care-registered individuals in England since 2020. IIS derives vaccine uptake data and patient identifiable information from the Data Provisioning Service at NHS England to offer improved depth of sociodemographic information (for example, sex, ethnicity, regional deprivation).
Detail on the various immunisation programmes covered by these data sources, and the relevant variables contained within each, are shown in Tables A2.1 and A2.2.
Relevant existing data and analyses for these programmes contained within quarterly and annual reports produced by UKHSA were sought and reproduced in this audit. Additional analyses of primary data were performed where necessary to explore variation in coverage according to individual equity factors. These reports, sources and additional analyses are described alongside the relevant findings in this audit.
Table A2.1. Immunisation programmes covered by the 3 main data sources
| Immunisation Programme | COVER | ImmForm | IIS |
|---|---|---|---|
| Targeted mpox | - | - | - |
| COVID-19 | - | ✓ | ✓ |
| Neonatal HepB | ✓ | ✓ | - |
| Pertussis pregnant women | - | ✓ | ✓ |
| Neonatal BCG | ✓ | - | - |
| Hexavalent DTaP/IPV/Hib/HepB | ✓ | ✓ | - |
| Rotavirus | ✓ | ✓ | - |
| MenB | ✓ | ✓ | - |
| MenACWY | - | ✓ | - |
| Hib/MenC | ✓ | - | - |
| PPV | - | ✓ | - |
| PCV | ✓ | - | - |
| dTaP/IPV and dTaP/IPV (pre-school booster) | ✓ | ✓ | - |
| MMR | ✓ | ✓ | ✓ |
| HPV | - | ✓ | - |
| HPV for GBMSM | - | - | - |
| Td/IPV (teenage booster) | - | ✓ | - |
| Seasonal influenza (adults and occupational groups) | - | ✓ | ✓ |
| Seasonal influenza (children) | - | ✓ | ✓ |
| Shingles | - | ✓ | - |
| RSV | - | ✓ | ✓ |
Table A2.2. CORE20PLUS framework variables included in the 3 main data sources
| Variable | COVER | ImmForm | IIS |
|---|---|---|---|
| Deprivation | No, but can link GP postcode to IMD | No, but can link GP postcode to IMD | Yes (IMD 2019) |
| Age | Yes (1, 2, 5 years) | Yes (age bands vary) | Yes (any from DoB) |
| Disability | - | Selected programmes only [footnote 1] | - |
| Gender reassignment | - | - | - |
| Marriage and civil partnership | - | - | - |
| Race | - | Selected programmes only [footnote 2] | ONS 2012 categories |
| Religion or belief | - | - | - |
| Sex | - | Selected programmes only [footnote 3] | Yes (male, female, unknown) |
| Sexual orientation | - | - | - |
| Geographical (rural, urban, coastal) | - | No, but can link GP postcode to ONS data | Yes, derivable from postcode of residence |
| Inclusion health / at-risk groups | - | Selected programmes only [footnote 4] | Yes (via CaaS flags) |
Literature review
A comprehensive narrative-style literature review was conducted to answer the following question:
- What is the extent and nature of difference in national immunisation programme coverage, disaggregated by individual vaccination programme, between CORE20PLUS populations and compared to the general population in England?
Here ‘extent’ refers to quantitative measures of coverage and its association with individual CORE20PLUS factors (for example, age, sex, deprivation, ethnicity and so on), while ‘nature’ refers to the qualitative determinants of uptake among CORE20PLUS populations (namely, facilitators and barriers).
An initial search was performed using PubMed® on 14 February 2025 and later supplemented by a search of wider databases by the Knowledge and Library Services at UKHSA. References were limited to those published in 2019 to 2025 as those published prior to 2019 were in scope for the previous audit. The full inclusion and exclusion are presented in Table A2.3.
The initial PubMed search terms were:
- (immunisation[Title] OR immunization[Title] OR vaccin*[Title])
AND
- (uptake[Title] OR equalit[Title] OR inequalit[Title] OR inequit[Title] OR equit[Title] OR disparit[Title] OR marginali[Title] OR inclu[Title] OR exclu[Title])
AND
- (engl[Title/Abstract] OR brit[Title/Abstract] OR “united kingdom”[Title/Abstract] OR UK[Title/Abstract])
AND
- (“2019/01/01”[Date - Publication] : “3000”[Date - Publication])
A total of 1,396 records were retrieved, of which 127 were retained after removing duplicates and screening for relevance. The reference list of each retained study was reviewed for additional records meeting the inclusion and exclusion criteria, identifying a further 64 relevant studies. Therefore, a total of 191 unique studies were included in this audit.
Figure A2.1 displays the vaccine antigens that were the focus of each of the 191 studies. It demonstrates that COVID-19 was the focus of more than half (n=97, 51%) of all included studies. Figure A2.2 displays the population groups that were the focus of each of the 191 studies.
Table A2.3. Literature review inclusion and exclusion criteria
| Element | Inclusion criteria | Exclusion criteria |
| Population | England, or a region/area thereof AND CORE20PLUS populations, or Protected characteristics, or Inclusion health groups, or Healthcare workers | Studies in multiple settings including England but where results in England are not reported separately, or Non-human populations |
| Intervention | Vaccination(s) | N/A |
| Comparator | None, or General population of England, or Sub-population of England | International population(s) |
| Outcomes | Vaccine uptake/coverage, or facilitators/barriers thereof | Vaccine efficacy/effectiveness, or Economic outcomes, or Clinical outcomes, or Policy/strategy/other analysis |
| Study type | Quantitative, or Qualitative, or Mixed methods, or Observational / natural experiments | Interventional,or Modelling, or Review,or Commentary/perspective/opinion articles, or Protocol, or Poster/conference abstracts |
Figure A2.1. Vaccines examined in the 191 studies included in the literature review
Infographic visualising the proportion of vaccines examined in the 191 studies included in the literature review. The most frequently examined vaccine is COVID-19 and the least common is pertussis.
Figure A2.2. Population groups examined in the 191 studies included in the literature review
Infographic visualising the rates at which specific population groups were examined in the literature review of 191 studies. The general population was most frequently examined, Older Adults were the least commonly examined population group.