COVID AND THE VACCINE - TRUTH, LIES, AND MISCONCEPTIONS REVEALED, page-39127

In rare cases, coronavirus vaccines may cause Long Covid–like symptoms
Brain fog, headaches, blood pressure swings are being probed by NIH and other researchers

“Now, a small number of other researchers worldwide is beginning to study whether the biology of Long Covid, itself still poorly understood, overlaps with the mysterious mechanisms driving certain postvaccine side effects.”

https://www.science.org/content/art...avirus-vaccines-may-cause-long-covid-symptoms