Young girl watching herself being injected with COVID-19 vaccine at a medical clinic

Between a third and a half of the populations of the four UK nations had not had the recommended number of COVID vaccinations and boosters by summer 2022, according to the first research study to look at COVID-19 vaccine coverage of the entire UK population.

These results can be used to help create health policy and public health interventions to improve vaccine uptake

Angela Wood

The findings, published today in The Lancet, suggest that more than 7,000 hospitalisations and deaths might have been averted in summer 2022 if the UK had had better vaccine coverage.

With COVID-19 cases on the rise and a new variant strain recently identified, this research provides a timely insight into vaccine uptake and hesitancy and could inform policy-makers.

The research relied on secure access to anonymised health data for everyone in all four nations of the UK, an advance which has only become possible during the pandemic.

Co-author Angela Wood, Professor of Health Data Science at the Victor Phillip Dahdaleh Heart & Lung Research Institute, University of Cambridge and Associate Director of the British Heart Foundation Data Science Centre said: “This is the first epidemiological study to use individual-level anonymised health data covering the entire UK population. We have created a detailed, UK-wide picture of who is under-vaccinated against COVID-19 and the associated risks of under-vaccination.

“These results can be used to help create health policy and public health interventions to improve vaccine uptake. This approach could be extended to many other areas of medicine with great potential for new discoveries in the understanding and treatment of disease.”

Early COVID-19 vaccine rollout began strongly in the UK, with over 90% of the population over the age of 12 vaccinated with at least one dose by January 2022. However, rates of subsequent booster doses across the UK were not fully understood until now.

Scientists from England, Scotland, Northern Ireland and Wales – led by Health Data Research UK (HDR UK) and the University of Edinburgh – studied securely-held, routinely collected NHS data from everyone over five years of age during 1 June to 30 September 2022. All data was de-identified and available only to approved researchers.

Data from across the four countries was then pooled and harmonised, a feat that was not possible until now. People were grouped by vaccine status, with under-vaccination defined as not having had all doses of a vaccine for which that a person was eligible.

The findings reveal that the proportion of people who were under-vaccinated on 1 June 2022 ranged between one third and one half of the population – 45.7% for England, 49.8% for Northern Ireland, 34.2% for Scotland and 32.8% Wales.

Mathematical modelling indicated that 7,180 hospitalisations and deaths out of around 40,400 severe COVID-19 outcomes during four months in summer 2022 might have been averted, if the UK population was fully vaccinated.

Under-vaccination was related to significantly more hospitalisations and deaths across all age groups studied, with under-vaccinated people over 75 more than twice as likely to have a severe COVID-19 outcome than those who were fully protected.

The highest rates of under-vaccination were found in younger people, men, people in areas of higher deprivation, and people of non-white ethnicity.

Researchers say the study – the largest ever study carried out in the UK – also ushers in a new era for UK science by overcoming challenges in uniting NHS data that is gathered and stored in different ways between devolved nations.

Professor Cathie Sudlow, Chief Scientist at Health Data Research UK and Director of the British Heart Foundation (BHF) Data Science Centre, said: “The infrastructure now exists to make full use of the potential of routinely collected data in the NHS across the four nations of the UK. We believe that we could and should extend these approaches to many other areas of medicine, such as cancer, heart disease and diabetes to search for better understanding, prevention and treatment of disease."

Professor Sir Aziz Sheikh, Director of the Usher Institute at the University of Edinburgh, HDR UK Research Director and study co-lead, said: “Large-scale data studies have been critical to pandemic management, allowing scientists to make policy-relevant findings at speed. COVID-19 vaccines save lives. As new variants emerge, this study will help to pinpoint groups of our society and areas of the country where public health campaigns should be focused and tailored for those communities.”

HDR UK COALESCE Consortium. Undervaccination and severe COVID-19 outcomes: meta-analysis of national cohort studies in England, Northern Ireland, Scotland, and Wales. Lancet; 16 Jan 2024; DOI:

Adapted from a release from HDR-UK

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