PLOS Medicine Author Interview: Steven Kerr, PhD

Below, Associate Editor Louise Gaynor-Brook interviews Steven Kerr, PhD, co-author of a research article describing the association between first dose ChAdOx1 and BNT162b2 COVID-19 vaccination and cerebral venous sinus thrombosis in England, Scotland, and Wales.

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’m a senior research fellow in the Centre for Medical Informatics at the Usher Institute, University of Edinburgh. How I ended up here is a slightly improbable tale, given my background.

I started out life as a physicist. After doing a PhD on quantum gravity and topological quantum field theory, I went on to a postdoc at Perimeter Institute for Theoretical Physics in Canada.

During that time, I developed a side interest in economics that started off as a pastime, but developed into some fruitful research ideas that I decided to pursue further. I moved back to Edinburgh to do a PhD working on game theory, modelling markets, and a grab-bag of other topics in economics. 

After a stint in the private sector as a data scientist, I was offered the opportunity to work on the EAVE-II project. EAVE-II is a collaboration between several Scottish universities and Public Health Scotland and led by Aziz Sheikh, that uses Scotland-wide data to track the COVID-19 pandemic and study vaccine effectiveness and safety. I feel very lucky to be working on this project with so many extraordinary collaborators who are producing exceptional and highly impactful work.

What are your scientific interests and what led you to investigate cerebral venous sinus thrombosis (CVST) following vaccination for COVID-19?

I’m interested in the role of data-science in improving people’s lives. I’m primarily motivated by work that has a real-world impact. However, I do still enjoy following theoretical research in particle physics, quantum gravity, and macroeconomics.

With regards to vaccine safety; there were reports of a potential link between CVST (a type of intracranial venous thrombosis) and vaccination with the Oxford-AstraZeneca vaccine in March 2021. CVST is a serious adverse event, and given the plan to mass-vaccinate the population of the UK, there was a clear scientific and policy interest in precisely determining the risks involved.

What is the most important take-home message from your study?

We found that the risk of CVST doubled in the four-weeks after receiving an Oxford-AstraZeneca vaccine. CVST is extremely rare, happening only 3-4 times per million people per year. Our results suggest one extra CVST event for every 4 million people vaccinated with the Oxford-AstraZeneca vaccine.

This additional risk should be weighed up against the benefits of vaccination. There is now clear evidence that vaccines are highly effective against hospitalisation and death due to COVID-19.

What are the clinical and global implications of your work?

Concerns over the safety of the Oxford-AstraZeneca vaccine led to the Joint Committee on Vaccination and Immunisation recommending against giving the Oxford-AstraZeneca vaccine to people aged under 40 years if an alternative is available. It is also not being routinely used as a booster currently.

I believe an age cut-off is a reasonable rule of thumb, but it is not easy to know where exactly to draw the line. The risk-benefit analysis is complex, and depends strongly on availability of alternative vaccines, waning in vaccine effectiveness and background infection rates, amongst others.

What’s next? What are the most interesting or exciting developments in your field?

I’m very interested in vaccine waning. There are some studies suggesting significant waning in effectiveness over the course of months. I am currently leading a UK-wide collaboration to answer this question, and hopefully the results of our investigation will be available soon!

My EAVE-II colleagues are working on research related to monoclonal antibodies, vaccine effectiveness in children and vaccine safety during pregnancy. I’m particularly interested to see research on the effectiveness of antiviral treatments, because it seems like a very promising direction for future interventions.

What do you feel are the benefits of publishing with a journal that supports open science practices?

I am a huge fan of open science practices, and it is one of the main reasons we chose to publish with PLOS Medicine. There is an ongoing replication crisis in medicine and the social sciences. Researchers face incentives that can lead to false findings being widely reported and accepted, with damaging consequences. All of this can be improved by engaging in transparent and reproducible research practices. I think we could certainly use more of PLOS’s open science approach!

What do you like to do when you’re not working on your research?

I am interested in effective altruism. It is a community of individuals trying to figure out how to use available resources to do the greatest good in the world. A lofty goal, and I certainly recommend checking them out. Since 2007, I have donated 20% of my income to charity. I am particularly interested in improving the welfare of factory farmed animals, who continue to be treated abysmally in their billions every year.

I am a keen martial artist. I enjoy training, and occasionally competing, in various combat sports, including boxing, freestyle wrestling, kickboxing and Brazilian jiu jitsu. There was a time in my life when I intended to be a professional mixed martial artist. On reflection, I think that using my head, rather than getting punched in it, was a wise career decision.

I play violin a little in my spare time, with varying levels of success. I occasionally give living-room concerts, but my neighbours probably prefer it when I’m analysing data.

I enjoy spending time with my niece and nephew. We enjoy doing wrestling moves together, and impromptu recreations of scenes from Disney movies.