New research involving more than 99 million people has linked very rare neurological, blood and heart-related medical conditions to COVID-19 vaccines.
But experts say the benefits still outweigh the risks. <of course they do>
More than 13.5 billion COVID-19 vaccine doses have been administered worldwide since 2020 and 71 per cent of the global population has received at least one dose.
The study aimed to inform future vaccine programs and rollouts.
Here's what the researchers found and what you need to know.
The study was the largest of its kind and included participants from Australia, Argentina, Canada, Denmark, Finland, France, New Zealand and Scotland who received a COVID-19 vaccine.
Researchers involved with the Melbourne-based Murdoch Children's Research Institute and Global Vaccine Network identified new 'vaccine safety signals', which highlight a potential link between a vaccine and a health condition.
A second study used a dataset involving 6.8 million Australians to examine the risk between the AstraZeneca COVID-19 vaccination and neurological conditions.
Researchers identified potential connections with the following medical conditions:
Myocarditis (inflammation of the heart muscle)
Pericarditis (swelling of the thin sac covering the heart)
Guillain-Barré syndrome (an attack of the immune system on the nerves)
Cerebral venous sinus thrombosis (a type of blood clot in the brain)
Acute disseminated encephalomyelitis (inflammation and swelling in the brain and spinal cord)