Characterising adults in Scotland who are not vaccinated against COVID-19

By Aug 10, 2022, 3 497 208 of the estimated 4·4 million adults living in Scotland had received three doses of a COVID-19 vaccine. However, a proportion of the adult population remains unvaccinated (defined as no record of any vaccine being administered) and susceptible to severe COVID-19 outcomes. Characterising this population can help to understand gaps in vaccine coverage and determinants of vaccine hesitancy and could support targeted public health messaging. Unlike the vaccinated population, on whom information is gathered at the point of vaccination, current estimates of the unvaccinated population are calculated using general practitioner (GP) records. However, complications arise because GP records can include people who have moved away from Scotland; estimates suggest that GP records contain a population 8% greater than National Records of Scotland population estimates.1Stockton D PHS reporting of cases, hospitalisations and deaths from COVID-19 by vaccine status—interpreting the data.https://publichealthscotland.scot/our-blog/2022/january/phs-reporting-of-cases-hospitalisations-and-deaths-from-covid-19-by-vaccine-status-interpreting-the-data/Date: Jan 19, 2022Date accessed: March 22, 2022Google Scholar We used data from linked national health records to estimate the number and describe the characteristics of adults living in Scotland for whom there is no record of any COVID-19 vaccination. This analysis was conducted using the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II) platform,2Simpson CR Robertson C Vasileiou E et al.Early pandemic evaluation and enhanced surveillance of COVID-19 (EAVE II): protocol for an observational study using linked Scottish national data.BMJ Open. 2020; 10e039097 Crossref Scopus (44) Google Scholar a national COVID-19 surveillance platform using anonymised individual patient-level records from all 940 general practices in Scotland, deterministically linked to multiple datasets recording morbidity, mortality, virology, vaccination, and prescribing (appendix p 1). Linkage was done with a unique identifier for each resident in Scotland who is registered with a GP. The EAVE II cohort includes all individuals registered with a GP in Scotland as of March 1, 2020, including those who have subsequently left Scotland without informing their GP. To exclude people no longer living in Scotland, we defined unvaccinated individuals as those without COVID-19 vaccination records who had at least one interaction with the National Health Service (NHS) Scotland since Jan 1, 2019. We used the EAVE II cohort at a cutoff date of Dec 8, 2020 (the start of the UK's vaccination programme). In the appendix (p 2) we outline the process of identifying the unvaccinated population. We excluded individuals who died of any cause before the cutoff date and those recorded as having left Scotland. As individuals younger than 18 years were only invited for vaccination more recently (between August, 2021, and March, 2022, depending on age), our analysis was restricted to adults aged 18 years and older. This identification process yielded 4 712 810 individuals who were recorded as eligible for COVID-19 vaccination. Linkage of vaccine eligibility data with COVID-19 vaccination records identified 842 029 (17·9%) of the 4 712 810 eligible individuals as having no record of vaccination. Among these 842 029 people, 86 489 (10·3%) had documented reasons for not receiving a vaccine, including immunisation contraindicated, immunisation consent not indicated, reason for non-vaccination, generally unwell, and vaccine refused by patient.3UK Health Security AgencyCOVID-19: the green book, chapter 14a.https://www.gov.uk/government/publications/covid-19-the-green-book-chapter-14aDate: Nov 27, 2020Date accessed: August 11, 2022Google Scholar Immunisation contraindicated was recorded for nearly one fifth of all unvaccinated individuals for whom a reason was documented. Laboratory records identified 254 049 individuals with no vaccination record who were tested at least once for SARS-CoV-2 by RT-PCR since the start of the pandemic. Non-hospital-based prescription records identified 416 499 individuals with no vaccination record who had been prescribed medication of any description since Jan 1, 2019. 285 647 unvaccinated individuals had interacted with the unscheduled care pathway (one or more of NHS 24, out-of-hours GP consultations, or the Scottish Ambulance Service), while 133 569 people with no vaccination record had at least one hospital admission according to the Scottish Morbidity Records. In total, 268 740 individuals with no evidence of vaccination were identified in any of the above data sources. 573 289 eligible individuals aged 18 years or older were identified as having no record of any COVID-19 vaccination in Scotland and at least one contact with NHS Scotland since Jan 1, 2019. We then excluded people who had died since the start of the vaccination programme, and those for whom immunisation contraindicated was recorded as the reason for non-vaccination. On Aug 10, 2022, our method identified 494 288 individuals with no record of any COVID-19 vaccination. This unvaccinated cohort contained similar proportions of males and females, with similar age distribution across both sexes (appendix pp 3–4). The mean age was 42·4 years. Most unvaccinated people lived in urban settings, and 143 558 (29·0%) of 494 288 unvaccinated individuals—compared with 719 251 (18·7%) of 3 847 789 vaccinated individuals—resided in areas ranked by the Scottish Index of Multiple Deprivation as containing the most deprived 20% of the Scottish population. On the basis of GP records, the majority (298 866, 60·5%) of 494 288 unvaccinated individuals were not known to have any comorbidities, compared with 1 988 751 (51·7%) of 3 847 789 vaccinated individuals, whereas 55 122 (11·2%) of 494 288 unvaccinated individuals were recorded as having three or more comorbidities, compared with 481 019 (12·5%) of 3 847 789 vaccinated individuals. The most frequently reported comorbidities among 494 288 unvaccinated individuals were chronic respiratory disease (77 643, 15·7%), depression (63 375, 12·8%), and hypertension (52 474, 10·6%). One in five (103 505, 20·9%) of 494 288 unvaccinated individuals were prescribed medications for conditions relating to the CNS, compared with 655 531 (17·0%) of 3 847 789 vaccinated individuals, with more than a third of this unvaccinated group (40 179 [38·8%] of 103 505) prescribed antidepressants. Multivariable logistic regression modelling was used to identify the factors most likely to predict COVID-19 vaccination. Male sex, high deprivation, living in large urban areas, being prescribed medication for CNS disorders, and having more than three comorbidities were most associated with unvaccinated status, although individuals with some comorbidities—such as hypertension, diabetes, and chronic respiratory disease—were more likely to be vaccinated. Previous UK data have reported on inequalities of COVID-19 vaccination coverage, with considerably lower uptake among some groups.4Perry M Akbari A Cottrell S et al.Inequalities in coverage of COVID-19 vaccination: a population register based cross-sectional study in Wales, UK.Vaccine. 2021; 39: 6256-6261Crossref PubMed Scopus (29) Google Scholar Notably, although increasing age and presence of comorbidities are among the most widely recognised risk factors for COVID-19 mortality,5Flook M Jackson C Vasileiou E et al.Informing the public health response to COVID-19: a systematic review of risk factors for disease, severity, and mortality.BMC Infect Dis. 2021; 21: 342Crossref PubMed Scopus (14) Google Scholar, 6Parohan M Yaghoubi S Seraji A Javanbakht MH Sarraf P Djalali M Risk factors for mortality in patients with coronavirus disease 2019 (COVID-19) infection: a systematic review and meta-analysis of observational studies.Aging Male. 2020; 23: 1416-1424Crossref PubMed Scopus (222) Google Scholar, 7Booth A Reed AB Ponzo S et al.Population risk factors for severe disease and mortality in COVID-19: a global systematic review and meta-analysis.PLoS One. 2021; 16e0247461 Crossref Scopus (251) Google Scholar people with a substantial number of comorbidities remained at increased risk of being unvaccinated. The limitations of our approach include a lack of ethnicity data, which are important because variations in vaccine uptake among different ethnic groups are known.8Gaughan C Razieh C Khunti K et al.COVID-19 vaccination uptake amongst ethnic minority communities in England: a linked study exploring the drivers of differential vaccination rates.J Public Health. 2022; fdab400 Crossref Scopus (4) Google Scholar Additionally, although our approach minimises false inflation of the number of unvaccinated people, some of these individuals will have had no recent interaction with the health-care system and so will remain undetected. Unvaccinated people might also be less likely to have health-seeking behaviour, reducing the chance of them being detected through this method.9Glasziou P McCaffery K Cvejic E et al.Testing behaviour may bias observational studies of vaccine effectiveness.J Assoc Med Microbiol Infect Dis Can. 2022; (published online July 12.)https://doi.org/10.3138/jammi-2022-0002PubMed Google Scholar Some individuals might have been vaccinated outside of Scotland, which was not captured in our analysis. Identifying people vaccinated in other countries will improve future estimates of unvaccinated populations. In summary, this national analysis revealed that, even after accounting for possible overinflation of population size, a considerable proportion of the adult population of Scotland remains unvaccinated against COVID-19. We also identified predictors of unvaccinated status, which can help with formulating a revised national vaccination strategy. For Scotland's COVID-19 vaccine dashboard see https://public.tableau.com/app/profile/phs.covid.19/viz/COVID-19DailyDashboard_15960160643010/Overview For Scotland's COVID-19 vaccine dashboard see https://public.tableau.com/app/profile/phs.covid.19/viz/COVID-19DailyDashboard_15960160643010/Overview AS and CR are members of the Scottish Government Chief Medical Officer's COVID-19 Advisory Group. AS is a member of the NERVTAG Risk Stratification Subgroup and an unfunded member of AstraZeneca's COVID-19 strategic consultancy group, the Thrombocytopenia Taskforce. CR is a member of the Scientific Pandemic Influenza Group on Modelling and the Medicines and Healthcare Products Regulatory Agency COVID-19 Vaccine Benefit and Risk Working Group. JLKM is a member of the COVID Scottish National Incident Management Team. CM reports research funding from the Medical Research Council, Health Data Research UK, National Institute for Health Research, and the Scottish Chief Science Office. All other authors declare no competing interests. EAVE II is funded by the Medical Research Council with the support of BREATHE, the health data research hub for respiratory health, which is funded through the UK Research and Innovation Industrial Strategy Challenge Fund and delivered through Health Data Research UK. Additional support was provided through Public Health Scotland and the Scottish Government Director-General Health and Social Care. The research for this Correspondence is part of the Data and Connectivity National Core Study, led by Health Data Research UK in partnership with the Office for National Statistics and funded by UK Research and Innovation. UA and CM acknowledge funding from Health Data Research UK (Measuring and Understanding Multimorbidity using Routine Data in the UK—HDR-9006; CFC0110). The funding source had no involvement in data collection, study design, data analysis, interpretation of findings, or the decision to publish this Correspondence. We thank Dave Kelly (Albasoft, Inverness, UK) for support with making primary care data available, Iain Mclaughlin (Public Health Scotland, Glasgow, UK) for help with the identification of the unvaccinated cohort, and James Pickett (Health Data Research UK, London, UK), Wendy Inglis-Humphrey, Vicky Hammersley, Maria Georgiou, Laura Gonzalez Rienda (Usher Institute, University of Edinburgh, Edinburgh, UK), Morna Coote, Amanda Burridge, Amie Wilson, and Megan Gorman (Public Health Scotland, Glasgow, UK) for project management and administration support. We acknowledge the support of the EAVE II Patient Advisory Group for their help with interpretation of findings and suggestions for dissemination and engagement. SSH and EH contributed equally. AS and CR contributed equally. Download .pdf (.46 MB) Help with pdf files Supplementary appendix