The new study, published in the journal Vaccine, is the largest study of its kind since the pandemic began and could reignite the debate over the risks and benefits of the vaccine.
Over the past three years, more than 13.5 billion doses of COVID-19 vaccines have been administered around the world. The World Health Organization recently announced that vaccination has saved at least a million and a half lives in Europe alone.
The study links vaccines to slight increases in neurological, blood and heart-related conditions such as myocarditis, pericarditis and Guillain-Barré syndrome.
Researchers stressed that an association between the vaccine and adverse side effects does not prove the vaccine caused them and that side effects were rare.