Doctor holding a vial of vaccine; new research finds that no cases of a rare blood disorder have been identified in the COVID-19 vaccinated population of Wales.

New research finds no cases of a 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.

Ronan Lyons, Professor of Public Health and Director of SAIL Databank at Swansea University, said:

“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.”

Read the full publication on Welsh Government’s Technical Advisory Cell pages

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.

Swansea University Medical School

Health Innovation - Swansea University research

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