Plain-English translation of NCT04992195 on ClinicalTrials.gov ↗ · Source last updated · Translation generated · How we translate trials
Read our Stroke research guide →Researchers studied how COVID-19 vaccines (specifically SinoVac or BioNTech) affected brain health in a group of Hong Kong residents. Participants received brain MRI scans before vaccination and again about 4 months after their second dose, along with cognitive (memory and thinking) assessments. The study compared vaccinated people to unvaccinated people who had never had COVID-19 to see if the vaccines had any impact on brain blood vessels or cognitive function.
After COVID-19 vaccines rolled out worldwide, some people had concerns about whether the vaccines could affect the brain or increase stroke risk. This study was designed to carefully examine whether this medication had any measurable effects on brain structure, brain blood vessels, or thinking skills in a real-world population.
Vaccinated participants received a second brain MRI scan about 4 months after their second vaccine dose, and had blood tests taken at baseline and again at that same 4-month timepoint. They also completed memory and thinking assessments (cognitive tests) at baseline, at 4 months, and then yearly for follow-up. In-person check-ups occurred at 4 months, with phone follow-ups every 6 months afterward. The control group (unvaccinated people) underwent similar baseline assessments and testing but without the post-vaccination follow-up scans.
AI-generated summary from trial data · Aug 5, 2026 · Not medical advice
Hong Kong