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Below, Associate Editor Louise Gaynor-Brook interviews William Whiteley, MRCP, PhD, co-author of a research article describing the association between ChAdOx1 and BNT162b2 COVID-19 vaccines and major venous, arterial, or thrombocytopenic events in England.
Please start off by telling us a little more about yourself – what’s your current role, where are you based, and what led you to a career in research?
I work as a Reader in Neurology at the University of Edinburgh, a consultant neurologist in NHS Lothian and a senior research fellow at the MRC Population Health Research Unit at the University of Oxford.
I was inspired to work in clinical epidemiology by David Sackett as a medical student, confirmed after working with Peter Sandercock and Joanna Wardlaw for my PhD on the prognosis of stroke, funded by the Chief Scientist’s Office.
What are your scientific interests and what led you to investigate venous, arterial, and thrombocytopenic events following vaccination for COVID-19?
I work in clinical epidemiology and clinical trials, particularly studying the causes, consequences and prevention of disability due to stroke and dementia.
At the start of the pandemic, I began to work with colleagues in the BHF Data Science Centre (led by Cathie Sudlow) to investigate the cardiovascular consequences of COVID-19 infection. After the first reports were made of thromboses in uncommon areas of the body after COVID-19 vaccination, we pivoted quickly to examine this question.
Using data from 46 million people, we wanted to find out how commonly people had thromboses in the cerebral veins after COVID-19 vaccination. We also wanted to see whether COVID-19 vaccines had effects on common thrombotic illnesses like heart attack and stroke.
What is the most important take-home message from your study?
Neither of the ChAdOx1-S (Oxford-AstraZeneca) or BNT162b2 (Pfizer-BioNTech) vaccines were associated with any increase in the average risk of major clots in the arteries or in the risk of major clots in the veins. We did find in people under 70 years old that there was a very small increase in the risk of hospitalisation because of clots in the cerebral veins (intracranial venous thrombosis) or hospitalisation because of low platelets with the ChAdOx1-S vaccine.
We did not directly compare the very small risk of these illnesses after COVID-19 vaccination with illnesses due to COVID disease. However, other groups have reported that during the height of the pandemic there were substantial reductions in COVID-19 illness and death after COVID-19 vaccination that outweighed any very small risks.
What are the clinical and global implications of your work?
Our results support the strategy of the UK Joint Committee on Vaccination and Immunisation (JCVI), which is to recommend BNT162b2 (or the Moderna mRNA-1273 vaccine) for people under the age of 40 years. However, this is because we are lucky enough to have a choice of vaccines in the UK. In other areas of the world where case numbers of COVID-19 are high and where there is no choice of vaccines, then the risk associated with ChAdOx1-S are extremely low – so low that they were not detected even in carefully monitored studies of tens of thousands of people.
What’s next? What are the most interesting or exciting developments in your field?
The availability of large linked health care datasets and medical informatics are making a huge difference to improving the quality of healthcare and testing new treatments. We have learnt a great deal during the pandemic about how to use these data for observational studies like this one, and for testing new treatments. It is essential we apply these lessons to other common illnesses that threaten our health, like stroke and dementia.
What do you feel are the benefits of publishing with a journal that supports open science practices?
I learnt a lot from the team about open science during this project. We used Github to publish our protocol phenotype lists and analytic code, and MedRxiv to pre-print the manuscript. Having the paper open to all in PLOS Medicine completes the open science chain!
To those who are nervous about taking an open science approach, I would say that it is simple (even for the non-technically minded) and leads to improvements in the whole research cycle.
What do you like to do when you’re not working on your research?
I’m lucky to live in a beautiful part of the UK. I like to get into nature with walking boots, a mountain bike or a wetsuit.