**1. Introduction**

The 2012 WHO Global Measles and Rubella Strategic Plan outlined the aim to achieve elimination of measles and rubella in at least five of the six WHO regions by the end of 2020 [1]. In 2018, the UK lost its measles elimination status, and since 2020 endemic transmission remains re-established [2]. Although there has not been a confirmed case of rubella in Wales (one of the four nations of the UK) since 2010, there have been regular and sometimes large outbreaks of measles [3–5]. A milestone achievement in the 2012 strategy was to ensure countries have at least a 95% uptake of two routine doses of measles- and rubella-containing vaccine by 2020. In line with these aims, the Wales Measles Elimination Task Group Action Plan 2019–2021 specifically highlighted the importance of increasing measles, mumps and rubella (MMR) vaccination coverage in young people [6].

Public Health Wales has produced COVER (Coverage of Vaccination Evaluated Rapidly) reports for over 30 years [7]. These reports present uptake of all routine childhood immunisations up to 16 years of age. These figures are fed back to vaccination providers to guide service improvements and requirements for catch-up. Data for these reports come from the National Community Child Health Database (NCCHD), which is a population register of all children in Wales registered with the National Health Service (NHS). Primary care doctors and nurses, school nurses and immunisation teams administering vaccines

**Citation:** Perry, M.; Cottrell, S.; Gravenor, M.B.; Griffiths, L. Determinants of Equity in Coverage of Measles-Containing Vaccines in Wales, UK, during the Elimination Era. *Vaccines* **2023**, *11*, 680. https:// doi.org/10.3390/vaccines11030680

Academic Editors: Ahmad Reza Hosseinpoor, M. Carolina Danovaro, Devaki Nambiar, Aaron Wallace and Hope Johnson

Received: 11 February 2023 Revised: 12 March 2023 Accepted: 15 March 2023 Published: 17 March 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

send completed vaccination forms to their health board child health office, detailing vaccinations that have been given. This information is then entered into the health board child health database, with the records extracted on a monthly basis and combined to form the NCCHD. The first dose of MMR is due at 12–13 months of age with a second routine dose at 3 years and 4 months, before school entry. Vaccination status checks are encouraged at routine primary care appointments, on entry to primary and secondary school, and alongside administration of teenage immunisations.

Routine reporting in Wales has shown that national coverage of one dose of MMR reported at two years of age has ranged between 86% and 98% over the last 20 years, whilst coverage of two doses at five years of age has varied between 71% and 94% [7]. Currently coverage is generally high; however, coverage in teenagers is lower and varies by region. Coverage in those aged older than 16 years is not routinely reported due to archiving of NCCHD data around this age. At an ecological level, there is lower vaccine uptake in more deprived areas compared to less deprived areas across all age groups [8]. Equitable access and coverage of vaccinations has been highlighted in the WHO European Immunization Agenda 2030 [9]. Socioeconomic factors are often associated with vaccination coverage for routine childhood immunisations. In developed countries, areas experiencing poverty, families that have a lower income, parents with a lower level of education and those experiencing unemployment are generally associated with lower vaccine uptake [10,11]. In contrast, higher education status [12] and higher income [13] have also been shown to be associated with lower uptake of vaccines in some populations. The association between poverty and low vaccine coverage is also seen in many low and middle income countries [14]. Vaccination coverage also appears to be lower in children resident in large or single parent households [11,15,16]. Demographic factors such as ethnicity, age of mother, country of birth, religion and gender have also been shown to be predictors of vaccination status [14,17–20].

Large ecological studies looking at routine childhood immunisations are still rare, and specific reasons for low uptake in Wales have not been previously explored. In this study we used data linkage of national datasets to identify factors associated with lower coverage of measles-containing vaccine, with the aim that this knowledge can be used to investigate what the barriers are for uptake of vaccination, develop interventions and prioritise areas for catch-up in a time of limited resources.
