Scientists have found two new, very rare side effects linked to the COVID-19 vaccine: a neurological disorder and spinal cord inflammation.
Researchers from the Global Vaccine Data Network examined the health records of over 99 million individuals from countries including Australia, Argentina, Canada, Denmark, Finland, France, New Zealand, and Scotland.
Published in the journal Vaccine, this study is the largest vaccine safety study to date.
The research looked at the occurrence of 13 medical conditions affecting the brain, blood, and heart in individuals after receiving the Pfizer, Moderna, or AstraZeneca vaccines, comparing these rates to those before the pandemic.
The study reaffirmed the rare occurrences of heart inflammation, specifically myocarditis and pericarditis, associated with Pfizer and Moderna vaccines.
Additionally, it discovered acute diffuse encephalomyelitis, a rare inflammation of the brain and spinal cord, as a side effect of the AstraZeneca vaccine, occurring at a rate of 0.78 cases per million doses.
The study also found that vaccines could cause Guillain-Barré syndrome.
This is when the immune system attacks nerve cells, which might lead to paralysis. However, most people get better. It also found a rare brain blood clot called cerebral venous sinus thrombosis.
Jim Battery, who co-directs the Global Vaccine Data Network, said it's important to use vaccines widely to spot rare side effects. This led to another study on 6.8 million people in Australia who got the AstraZeneca vaccine.
"It is impossible to detect rare side effects until millions of people use the vaccine. No clinical trial can be so large-scale," Bateri said.
Julie Leask, a vaccine expert at the University of Sydney, mentioned that catching COVID-19 is much riskier than getting the vaccine when it comes to these rare conditions.
