Long COVID Syndrome refers to persistent, multi-system symptoms such as fatigue, cognitive impairment, dyspnea, and gastrointestinal issues lasting weeks or months after acute COVID-19, regardless of initial illness severity. Risk factors include female gender, advanced age, comorbidities, and hospitalisation. The World Health Organization defines it as a “post-COVID-19 condition” with symptoms persisting for at least two months after onset. Prevalence estimates vary from 10% to 87%, marking it a significant global health issue. Despite vaccination and antiviral efforts, long COVID remains prevalent, increasingly linked to prolonged exposure to the SARS-CoV-2 spike protein. This protein is central to the emerging condition known as post-COVID-19-vaccine syndrome (PCVS), which mirrors long COVID symptoms and may share mechanisms such as immune dysregulation, inflammation, and vascular injury. The recombinant spike protein used in vaccines has been detected in tissues months post-vaccination, raising concerns about its persistence and pathogenic potential. Autopsy studies have revealed spike proteins in vital organs without signs of active infection, suggesting vaccine-related involvement. These findings emphasize the urgent need for research into targeted therapies and accessible treatment strategies for both long COVID and PCVS. However, clinical trials remain scarce, highlighting a critical gap in addressing the long-term consequences of COVID-19 and its vaccination.