Association of Spike protein with COVID-19 vaccine side effects

COVID-19 vaccination has prevented many severe illnesses and deaths, but a small number of people report debilitating symptoms that last for months after vaccination. These symptoms can include severe fatigue, brain fog, dizziness, and nerve pain. The mechanisms behind these persistent symptoms remains unclear. This study will examine whether a component of SARS-CoV-2-the spike protein-can still be detected in the blood of people with ongoing symptoms, and whether higher spike levels are linked to greater symptom severity. Adults with symptoms lasting at least 3 months after COVID-19 vaccination will be compared with vaccinated people of similar age and sex who did not develop chronic symptoms. Blood samples (serum and plasma) will be collected to measure spike protein and COVID-19 antibodies. Participants' medical charts will be reviewed to capture health history, vaccination and infection timelines, medications, and symptoms. Because standardized symptom severity scores are not recorded in charts, the study will develop a chart-based severity index using symptom types, impact on work/daily activities, and healthcare visits and tests. The aim is to clarify whether spike protein (an objective biomarker) is associated with post-vaccination syndrome. This work will contribute to improving recognition of post-vaccination syndrome, patient care, vaccination policies and public health decision-making.