

New research finds no cases of the rare blood disorder have been identified in the COVID-19 vaccinated population of Wales.
A rapid evaluation of the Welsh healthcare data was undertaken to respond to an urgent request for information on COVID vaccine-related blood clots. The focus of the analysis was to understand whether reports of a small number of rare blood clotting disorders (venous sinus thromboembolism) reported in Norway and Germany, had also been observed in vaccinated individuals in Wales.
Scientists at the SAIL (Secure Anonymised Information Linkage) Databank in Swansea University undertook the analysis using anonymised patient data in its secure, Trusted Research Environment that’s accredited to the highest international standard (ISO 27001) for data management.
Data was analysed for the period between 1 January 2019 and 31 January 2021 to determine whether there had been an increase in the numbers of the rare blood clotting disorder, venous sinus thromboembolism, recorded during the initial vaccine roll-out. In the 25 months period, a total of 19 cases of the disorder were recorded. No new cases of venous sinus thromboembolism were recorded in individuals who had received a vaccine in this period. Seven people with a previous diagnosis of this condition had been vaccinated by 31 January 2021.
Between 4 December 2020 and 31 January 2021, 440,000 people had at least one dose of the vaccine as recorded in the Welsh COVID Vaccine data. Of these, 180,000 people received the Oxford Astra Zeneca vaccine and 260,000 received the Pfizer Vaccine.
“This is an important finding about the safety of the vaccines in use in Wales. We found no cases of this rare clotting disorder amongst the first 440,000 people who were vaccinated up until the end of January. We will continue to interrogate more data as it becomes available and as more people are vaccinated. This is very good news for our collective efforts to emerge from this pandemic and save more lives through the vaccination programme.”
– Swansea University Professor of Public Health & Director of SAIL Databank, Ronan Lyons.
Venous sinus thromboembolism is a condition that is diagnosed in hospital. There is a delay in detailed coding of hospital records which is why the analysis was completed up until end of January 2021 but it will be updated going forward.
This condition is rare, with fewer than 1 person per month diagnosed in the Welsh population of 3.2 million people.
Work is ongoing in Wales to monitor the data from the vaccine programme using the linked data assets that we have in Wales.
Read the full publication here on Welsh Government’s Technical Advisory Cell pages:
Acknowledgements
This study makes use of anonymised data held in the Secure Anonymised Information Linkage (SAIL) Databank. We would like to acknowledge all the data providers who make anonymised data available for research. The collaboration was led by the Swansea University Health Data Research UK team under the direction of the Welsh Government Technical Advisory Cell (TAC) and includes the following groups and organisations: the Secure Anonymised Information Linkage (SAIL) Databank, Administrative Data Research (ADR) Wales, NHS Wales Informatics Service (NWIS), Public Health Wales, NHS Shared Services Partnership and the Welsh Ambulance Service Trust (WAST). All research conducted has been completed under the permission and approval of the SAIL independent Information Governance Review Panel (IGRP) project number 0911. The team at Swansea University who support and maintain the One Wales collaboration, Con-COV project and associated COVID-19 e-cohorts and data is Ashley Akbari, Gareth Davies, Rowena Griffiths, Jane Lyons, Ronan Lyons, Laura North and Fatemeh Torabi. Controlling COVID19 through enhanced population surveillance and intervention (Con-COV): a platform approach, is funded by the UKRI Medical Research Council, grant reference: MR/V028367/1.
This work was supported by Health Data Research UK, which receives its funding from HDR UK Ltd (HDR-9006) funded by the UK Medical Research Council, Engineering and Physical Sciences Research Council, Economic and Social Research Council, Department of Health and Social Care (England), Chief Scientist Office of the Scottish Government Health and Social Care Directorates, Health and Social Care Research and Development Division (Welsh Government), Public Health Agency (Northern Ireland), British Heart Foundation (BHF) and the Wellcome Trust.
This research has been supported by the ADR Wales programme of work. The ADR Wales programme of work is aligned to the priority themes as identified in the Welsh Government’s national strategy: Prosperity for All. ADR Wales brings together data science experts at Swansea University Medical School, staff from the Wales Institute of Social and Economic Research, Data and Methods (WISERD) at Cardiff University and specialist teams within the Welsh Government to develop new evidence which supports Prosperity for All by using the SAIL Databank at Swansea University, to link and analyse anonymised data. SAIL Databank receives core funding from the Welsh Government’s Health and Care Research Wales and funding from UK Research and Investment (UKRI). ADR Wales is part of the Economic and Social Research Council (part of UK Research and Innovation) funded ADR UK (grant ES/S007393/1).