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Research at a Glance:
- An international study has linked several 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 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. It found vaccine safety signals were warranted for myocarditis, pericarditis, Guillain-Barré syndrome and cerebral venous sinus thrombosis
- A new signal for acute disseminated encephalomyelitis was also detected and a follow up study in Victoria, confirmed the association along with transverse myelitis
- However, the findings translated to an extremely small risk with any potential link needing to be weighed against the protective benefits of vaccination against COVID-19. The researchers unequivocally supported the global COVID-19 vaccination program
- The researchers stated the findings would help clinicians better inform their patients of the benefits and potential side effects associated with vaccines
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 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 Global Vaccine Data Network, said the size of the population in these studies increased the possibility of identifying very rare vaccine safety signals as rapidly as possible.
The Global Vaccine Data Network was created in 2019 to assess vaccine effectiveness in diverse settings and to map vaccine 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
Hannah Morgan, MCRI Health Informatics researcher
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Professor Julie Leask is a social scientist specialising in immunisation in the School of Public Health, University of Sydney and Sydney Institute for Infectious Diseases. She co-leads the Social and Behavioural Insights in Immunisation research group.
Australian researchers have been keeping careful track of the safety of the COVID-19 vaccines. We saw this in 2021 when a rare clotting syndrome led to a limitation on who should get the AstraZeneca vaccine. In this study, researchers found a link between some of the COVID-19 vaccines and other rare serious conditions.
Some of the conditions like myocarditis were already known. Some are so rare that the link only shows up when you connect data on hospitalisations with data on vaccinations. Two possible new adverse events have been raised using this linked data - Acute disseminated encephalomyelitis (ADEM) and transverse myelitis. These are very rare inflammatory conditions that affect the brain and/or spine. In a study from Australia by some of the same authors, the AstraZeneca vaccine appears to have increased the risk of ADEM to an estimated 0.78 per million doses in Australia – which is still very rare. However, the broader global study showed a link between ADEM and one of the mRNA vaccines.
Getting COVID disease increases the risk of these conditions much more than a vaccine. That is why, like with many medicines, we weigh up risks against benefits. Our vaccination safety experts – some of whom were involved in this study - contribute to our latest vaccination recommendations through the Australian Technical Advisory Group on Immunisation. They carefully weigh vaccine risk and benefit in populations and that is reflected in our current recommendations, which are tailored to need and risk. It’s very important for people to check if they or a loved one are in the groups recommended for a booster, like older people or those medically at risk. It could save them from getting very sick or even save their life.
Australia has robust vaccination programmes that carefully monitor vaccination safety and adjust any vaccine recommendations as needed. Identifying rare but serious side effects is one part of that. Another part is looking after the very small number of people who get a serious side effect. Australia introduced a vaccine injury claims scheme for only the COVID vaccines in 2021. That scheme is due to end in April. Government is yet to announce their plan going forward.
The Australian government should extend its COVID-19 vaccine injury compensation scheme, due to end in April. It should continue to include COVID-19 vaccines but extend it to all vaccines recommended on our national program. People vaccinate as part of a social contract. Very rarely a person will get a serious side effect. It is right for the government to compensate for the costs from rare vaccine side effects, which can include care, medical expenses, and time away from work.
Associate Professor Vinod Balasubramaniam is a Molecular Virologist and the Leader of the Infection and Immunity Research Strength from the Jeffrey Cheah School of Medicine & Health Sciences at Monash University in Malaysia
An international coalition of vaccine experts conducted a comprehensive analysis across eight countries, examining 99 million vaccine recipients to assess potential associations between COVID-19 vaccinations and various medical conditions. This extensive study, the largest of its kind, revealed slight increases in neurological, blood, and heart-related conditions following COVID-19 vaccination, while emphasizing the vaccines' effectiveness in safeguarding against severe illness, death, and the lingering symptoms of long COVID.
With over 13.5 billion COVID-19 vaccine doses administered worldwide and approximately 71% of the global population having received at least one dose, the impact on public health has been profound, saving numerous lives and mitigating the severity of symptoms associated with the virus.
In my perspective, when confronting significant public health crises like the pandemic, it becomes imperative to evaluate the balance between benefits and risks. COVID-19 vaccines serve the crucial purpose of preventing severe infections, with studies affirming the efficacy of vaccines from Moderna, Pfizer-BioNTech, and AstraZeneca in reducing severe illness, hospitalizations, and fatalities.
Data underscores that the likelihood of experiencing a neurological event following a COVID-19 infection is markedly higher, up to 617 times, compared to post-vaccination occurrences. Similarly, the risk of myocarditis is greater after a COVID-19 infection than following vaccination, with statistics indicating a risk of 35.9 cases per 100,000 individuals after the second vaccine dose, compared to 64.9 per 100,000 after contracting COVID-19.
Furthermore, research published in Neurology in 2023 demonstrates that the risk of Guillain-Barre syndrome is six times higher after COVID-19 infection compared to vaccination, where the latter presents a risk 0.41 times greater than the control group. Considering the scale of vaccination efforts, with 13 billion doses administered and approximately 2,000 reported cases of adverse events, COVID-19 vaccines have contributed significantly to preventing over 19 million deaths globally, including three million in the United States alone.
Based on comprehensive data and numerous publications, I firmly advocate that the risk of adverse events remains substantially lower with vaccination compared to contracting SARS-CoV-2 (COVID-19). Thus, vaccination remains the vastly safer choice for protecting against COVID-19.
