International researchers have linked very rare neurological, blood and heart related medical conditions to COVID-19 vaccines by using big data to better understand and monitor vaccine safety.

The research, involving Murdoch Children’s Research Institute (MCRI) and published in Vaccine, has identified new and previously recognised vaccine safety signals, which highlight a potential link between a vaccine and a health condition, contributing crucial information to COVID-19 vaccine programs and for future mass vaccine rollouts.

The researchers are collaborators to the Global Vaccine Data Network (GVDN), which has used an electronic database to leverage large amounts of data to evaluate COVID-19 vaccine safety. 

The largest study of its kind involved more than 99 million people from Australia, Argentina, Canada, Denmark, Finland, France, New Zealand and Scotland who received a COVID-19 vaccine. 

The analysis found vaccine safety signals were warranted for myocarditis (inflammation of the heart muscle) and pericarditis (swelling of the thin sac covering the heart) after mRNA vaccines and Guillain-Barré syndrome (where the immune system attacks the nerves) and cerebral venous sinus thrombosis (a type of blood clot in the brain) after an AstraZeneca vaccine. A new signal for acute disseminated encephalomyelitis (inflammation and swelling in the brain and spinal cord) was also detected, warranting further investigation.

But the findings translated to an extremely small risk with any potential link needing to be weighed against the well-established protective benefits of vaccination against COVID-19.

An accompanying paper in Vaccine, led by MCRI, confirmed the increased risk between receiving an AstraZeneca vaccine and acute disseminated encephalomyelitis as well as transverse myelitis (spinal cord inflammation).

The study, using a dataset involving 6.8 million Australians, is the first to measure the association between AstraZeneca COVID-19 vaccination and the two neurological conditions.

Acute disseminated encephalomyelitis usually impacts young children and adolescents. However, COVID-19 vaccination in Australia was recommended from 12 years and over, with only younger children in high-risk groups encouraged to get vaccinated. mRNA vaccines are now recommended for everyone aged over five years in Australia.

More than 13.5 billion COVID-19 vaccine doses have been administered worldwide since 2020.

MCRI Professor Jim Buttery, who is also a co-director of the GVDN, said the size of the population in these studies increased the possibility of identifying very rare vaccine safety signals as rapidly as possible.

Image: Professor Jim Buttery

The GVDN was created in 2019 to assess vaccine effectiveness in diverse settings and to map links to serious side effects.

"There was a pressing need for comprehensive vaccine safety monitoring as very rare adverse events following COVID-19 vaccination were starting to come to light after administration to millions of people,” Professor Buttery said.

“Vast and diverse datasets can play a key role in early detection of potential vaccine safety signals or when regulatory and public health agencies need rapid assessment of an emerging safety signal. These evaluations are not only valuable early-on in large-scale vaccine deployment, but also as the vaccination program matures, especially if they can be conducted in a multi-country context.

“The findings will also help clinicians better inform their patients of the benefits and potential side effects associated with vaccines and boost public vaccine confidence.”

Publication 1: K. Faksovaa, D. Walsh, Y. Jiang, J. Griffin, A. Phillips, A. Gentile, J. C. Kwong, K. Macartney, M. Naus, Z. Grangek, S. Escolano, G. Sepulveda, A. Shetty, A. Pillsbury, C. Sullivan, Z. Naveed, NZ. Janjua, N. Giglio, J. Perälä, S. Nasreen, H. Gidding, P. Hovi, T. Vor, F. Cui, L. Deng, L.Cullen, M. Artamar, H. Lu, H. Clothier, K. Batty, J. Paynter, H. Petousis-Harris, J. Buttery, S. Black and A. Hviid. ‘COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals,’ Vaccine. DOI: 10.1016/j.vaccine.2024.01.100

Publication 2: Hannah J Morgan, Hazel J Clothier, Gonzalo Sepulveda Kattan, James H Boyd and Jim P Buttery. ‘Acute Disseminated Encephalomyelitis and Transverse Myelitis following COVID-19 vaccination – a self-controlled case series analysis,’ Vaccine. DOI: 10.1016/j.vaccine.2024.01.099

Available for interview:

Professor Jim Buttery, MCRI Group Leader, Health Informatics and Centre for Health Analytics, Melbourne Children's Campus

Hannah Morgan, MCRI Health Informatics researcher

Media Contact:

Murdoch Children's Research Institute
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About MCRI

Murdoch Children's Research Institute is the largest child health research institute in Australia committed to making discoveries and developing treatments to improve child and adolescent health in Australia and around the world. They are pioneering new treatments, trialling better vaccines and improving ways of diagnosing and helping sick babies, children and adolescents. It is one of the only research institutes in Australia to offer genetic testing to find answers for families of children with previously undiagnosed conditions.

Funding publication 1:

The GCoVS project is supported by the Centers for Disease Control and Prevention (CDC) of the US Department of Health and Human Services (HHS) as part of a financial assistance award totalling US$10,108,491 with 100 per cent funded by CDC/HHS. The contents are those of the author and do not necessarily represent the official views of, nor an endorsement by, CDC/HHS, or the US Government. For more information visit The Centers for Disease Control and Prevention. The Ontario site contributing to this study was supported by Public Health Ontario and by the ICES, which is funded by an annual grant from the Ontario Ministry of Health. JCK is supported by a Clinician-Scientist Award from the University of Toronto Department of Family and Community Medicine.

Funding publication 2:

The Victorian Department of Health provides funding to SAEFVIC.