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Study aims to understand why COVID-19 vaccines can lead to very rare blood clotting with low platelets

Press release issued: 30 November 2021

A group of 11 institutions, led by the University of Liverpool and including the University of Bristol, is seeking to understand the very rare, but very serious, condition of blood clotting with low platelets in the general population, in COVID-19 infection, and potentially following vaccination.

The vast majority of people who experience a side effect from COVID-19 vaccination have  only mild reactions lasting for two or three days. However, in March 2021 reports of small numbers of people being admitted to hospital predominantly after the Oxford/AstraZeneca vaccine with what could potentially be a very rare side effect of vaccination began to emerge. These people had blood clots in the major veins in the brain, abdomen, or elsewhere in the body, but at the same time a low level of platelets – which are responsible for clotting – in the blood.

The group of researchers, supported by a wide range of collaborators within the NHS and national agencies, will work together to study the mechanisms underlying the occurrence of blood clots with low platelets – known as thrombotic thrombocytopenia syndrome (TTS).  This project is supported by the National Institute for Health Research and backed by £1.6 million of government funding from the Vaccine Taskforce.

Bristol's involvement in the study, led by Professor Jonathan Sterne, will be to look at the association of COVID-19 vaccination with cardiovascular events after vaccination by analysing very large (population-level) datasets.

Read the full University of Bristol press release

Further information

About the National Institute for Health Research (NIHR)
The mission of the National Institute for Health Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:

  • Funding high quality, timely research that benefits the NHS, public health and social care;
  • Investing in world-class expertise, facilities and a skilled delivery workforce to translate discoveries into improved treatments and services;
  • Partnering with patients, service users, carers and communities, improving the relevance, quality and impact of our research;
  • Attracting, training and supporting the best researchers to tackle complex health and social care challenges;
  • Collaborating with other public funders, charities and industry to help shape a cohesive and globally competitive research system;
  • Funding applied global health research and training to meet the needs of the poorest people in low- and middle-income countries.

NIHR is funded by the Department of Health and Social Care. Its work in low- and middle-income countries is principally funded through UK Aid from the UK government.

About National Institute for Health Research Bristol Biomedical Research Centre (NIHR Bristol BRC)
NIHR Bristol Biomedical Research Centre’s (NIHR Bristol BRC) innovative biomedical research takes science from the laboratory bench or computer and develops it into new drugs, treatments or health advice. Its world-leading scientists work on many aspects of health, from the role played by individual genes and proteins to analysing large collections of data on hundreds of thousands of people. Bristol BRC is unique among the NIHR’s 20 BRCs across England, thanks to its expertise in ground-breaking population health research.

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