The previously-unknown condition - dubbed 'post-vaccination syndrome' - appears to cause brain fog, dizziness, tinnitus and exercise intolerance.
Some sufferers also show distinct biological changes, including differences in immune cells and the presence of coronavirus proteins in their blood, years after taking the shot.
The condition also appears to reawaken a dormant virus in the body called Epstein-Barr which can cause flu-like symptoms, swollen lymph nodes and nerve issues.
The full results of the small study have not yet been published, and the Yale experts emphasized the results 'are still a work in progress.'
Yet the findings, from a well-respected institution, suggest more research on post-vaccination syndrome is needed, independent experts said. The next phase of the research will be to ascertain how widespread the condition is and who is most at risk.
Researchers at Yale University in a small, yet to be published study found that Covid vaccines were linked to a rare 'post-vaccination syndrome' causing 'distinct biological changes' to the body (stock image)
Thousands of people have said that Covid vaccines injured them since the shots were rolled out in 2021. But the fragmented nature of the US healthcare system makes it challenging to identify rare side effects.
Larger studies have failed to separate the symptoms suffered after Covid vaccination from unrelated illnesses that would have occurred regardless.
Dr Akiko Iwasaki, study author and immunologist at Yale University, said: 'This work is still in its early stages, and we need to validate these findings....<<<Read More>>>...