Ground-breaking study reveals how COVID-19 vaccines prevent severe disease

2 May 2024

A landmark study by scientists at the University of Oxford, has unveiled crucial insights into the way that COVID-19 vaccines mitigate severe illness in those who have been vaccinated.

Despite the global success of COVID-19 vaccination campaigns, concerns remain around the continued spread of this disease including in vaccinated individuals. For this reason, researchers at the Oxford Vaccine Group conducted an extensive investigation into the human immune response to COVID-19, in both vaccinated and unvaccinated individuals.

Employing contemporary “big-data” analyses, scientists can find novel associations between fundamental biological entities and indicators of the severity of a disease — to build patterns of health and disease. Results of this study categorically show a reduction in indicators of disease severity in those who had received the vaccine, demonstrating that the harmful inflammatory reaction to COVID-19 is less severe in those who have been vaccinated, when compared with those who haven’t.

Professor Daniel O'Connor, Head of Bioinformatics at the Oxford Vaccine Group (OVG), led the study. He said: “These results confirm the efficacy of vaccination and its pivotal role in reducing the harmful consequences associated with COVID-19. The results of our research highlight the ChAdOx1 nCoV-19 vaccine's ability to modulate harmful responses to the SARS-CoV-2 virus, and therefore to reduce the severity of illness. The implications of these findings are far-reaching, offering evidence that is fundamental to future vaccine development and pandemic mitigation strategies. It also provides valuable guidance for policymakers and public health experts.”

Professor Sir Andrew Pollard, Ashall Professor of Infection and Immunity and Director of the Oxford Vaccine Group, said: “Better understanding of how vaccines can reduce the severity of infections caused by viruses like COVID-19 is a key part of our preparedness to make effective vaccines against the next pandemic threat. Ongoing research is critical as we know the next one is coming but we don’t know which virus or when it will be.”

The study employed state-of-the-art technologies, including RNA-sequencing (to capture the level of genes produced by blood cells), to achieve these results. While the findings are promising, the study acknowledges limitations such as a focus on mild cases and sample size constraints, highlighting the need for further research utilising advanced techniques to enhance resolution.

Key findings from the study include:

  • Identification of unique responses to COVID-19 among vaccinated individuals, highlighting the vaccine's influence on responses to this disease.
  • Demonstrated reduction in harmful responses associated with COVID-19 severity in recipients of the ChAdOx1 nCoV-19 vaccine compared with unvaccinated counterparts.
  • COVID-19 in vaccinated individuals resulted in less COVID-19-induced blood cell count changes.
  • Correlation between decreased levels of a particular class of molecules in blood (microRNAs) and elevated levels of inflammation, suggesting a regulatory role for these molecules in inflammatory responses to viral infection.

Funding for the study was provided by various organisations, including the National Institute for Health Research (NIHR), Oxford Biomedical Research Centre, and Oxford Nanopore Technologies. Notably, the ChAdOx1 nCoV-19 randomised controlled trials received support from UK Research and Innovation, NIHR, Coalition for Epidemic Preparedness Innovations, Bill & Melinda Gates Foundation, among others.

Notes for Editors

For media queries or to schedule interviews please contact Dr Adriaan Louis Taljaard, Manager Strategic Communications (Vaccines), Oxford University: [email protected]
Link to the research paper: Multi-omics analysis reveals COVID-19 vaccine induced attenuation of inflammatory responses during breakthrough disease

About Oxford Vaccine Group (OVG)
The Oxford Vaccine Group (OVG) designs and conducts studies of new and improved vaccines for children and adults around the world and is based in the Department of Paediatrics at the University of Oxford. Visit our website and follow us on X.

About the Department of Paediatrics
The Department of Paediatrics is a world leader in child health research and hosts internationally renowned programmes in drug development, gastroenterology, haematology, HIV, immunology, neuroimaging, neuromuscular diseases and vaccinology. Its work spans from early proof-of-concept and fundamental science all the way up to its application in clinical settings.
The Department aims to shape the landscape of medical science by positively impacting the lives of millions of children through its global research programmes, academic resources and commitment to success. With research facilities in the UK and abroad, the Department of Paediatrics works on an international scale, and has a strong, collaborative network with the medical science community across the globe.

About the University of Oxford
Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the eighth year running, and number 3 in the QS World Rankings 2024. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.
Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.
Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 300 new companies since 1988. Over a third of these companies have been created in the past five years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing £15.7 billion to the UK economy in 2018/19, and supports more than 28,000 full time jobs.