Impact of COVID-19 Vaccines on Cerebrovascular Health

Safe and effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines may reduce the transmission of and achieve population immunity against the COVID-19 pandemic, which accounted for more than 3.75million deaths worldwide. With World Health Organization's (WHO) effort on ensuring equitable access to COVID-19 vaccines, vaccination rate may increase in the near future. On the other hand, vaccination hesitancy has emerged as a major hindrance on the global vaccination campaigns in certain areas due to safety concerns, social factors, and public health policies. For instance, a recent survey conducted in Hong Kong showed a low vaccine acceptance rate of 37%. Long-term safety concerns and post-vaccination events relayed by the social media maybe reasons for vaccination hesitancy. Among which, cerebrovascular accidents (CVA) after vaccination were one of the most frequently reported post-vaccination events. These reports ranged from ischemic strokes in elderly patients with multiple cardiovascular co-morbidities, to hemorrhage strokes in otherwise "young-and-fit" adults. While many of these events were investigated by the COVID-19 immunization expert committee, an important premise to address the apprehension of CVA after vaccination is the provision of evidence-based information of the impact of COVID-19 vaccines on brain health. In this prospective, longitudinal, observational study, we aim to elucidate the relationship between COVID-19 vaccines and cerebrovascular health in healthy citizens in a population-based cohort.

NCT Number	NCT04992195
Lead Sponsor	Chinese University of Hong Kong
Conditions	Stroke, Stroke, Acute, Stroke, Ischemic, Dementia, Brain Ischemia, Alzheimer Disease, Brain Diseases, Major Adverse Cardiovascular Event +2 more
Enrollment	415 participants
Start Date	2021-07-05
Primary Completion	2026-03-31 (estimated)
Study Completion	2026-03-31 (estimated)
Updated on ClinicalTrials.gov	2026-07-30