COVID Vaccine Blood Clots and Microclots: What the Research Shows
Updated October 30, 2026
Short answer
Research hasn't established that COVID-19 vaccines cause microclots as of October 2026. A 2026 study of 14 people with persistent post-vaccination symptoms found amyloid-positive microclot material compared with 16 controls, but prior infection couldn't be excluded. This site explains that research, and the treatments being studied, in plain language.
Are microclots the same as vaccine blood clots?
Microclots aren't the same as the large clots behind a deep vein thrombosis or pulmonary embolism. A large clot blocks a named vein or artery and shows up on ultrasound, CT or D-dimer, while a fibrin amyloid microclot measures roughly 1 to 200 micrometres and is seen only under a microscope with a Thioflavin T stain.
Most search results for COVID vaccine blood clots discuss large clots. This site focuses on microclots: the microscopic, amyloid-positive kind studied in Long COVID and post-vaccination research.
What does the research say about microclots after vaccination?
Lab studies show spike protein S1 and a spike fragment called Spike685 can make fibrin resist breakdown, and mRNA vaccines encode that same spike sequence. In 2026, Waters and colleagues found amyloid-positive microclot material and coagulation changes in 14 people with post-vaccination or post-infection syndrome, compared with 16 controls.
The cohort was small, and the authors couldn't rule out unrecognised infection, so a vaccine-specific cause remains unproven. The full review is on our partner site: microclots and the COVID vaccine.
Which treatments are being studied?
Four approaches to microclots are being studied, none of them proven in randomized trials. Ultrasound has lab-only results from 2025 and 2026.
Ultrasound for blood clots
Ultrasound is how doctors look for a large clot in a deep vein. In 2025 and 2026 lab-on-chip studies, low-frequency ultrasound also broke up amyloid microclots. It hasn't been tested in people.
Read moreNattokinase and lumbrokinase
Nattokinase broke down lab-made microclots in one 2024 preprint, but didn't significantly shrink plasma-derived microclots in a 2026 study. No study has measured microclots in people taking it.
Research review on amyloid-test.comPlasmapheresis and DFPP
Double filtration plasmapheresis filters large molecules such as fibrinogen and antibodies out of plasma, in courses of 2 to 4 weeks at Edogawa Hospital in Tokyo. Groups in Tokyo, Dresden and Berlin report improvements, but the data are early and mostly uncontrolled.
Research review on amyloid-test.comTriple anticoagulant therapy
Triple therapy combines clopidogrel, aspirin and apixaban. The only published data come from an uncontrolled cohort of 91 patients, there are no randomized trials, and the combination carries real bleeding risk.
Research review on amyloid-test.comSee all treatments for blood clots and microclots
Can you test for microclots?
Standard clotting tests such as D-dimer don't detect amyloid microclots; they're seen with Thioflavin T fluorescence microscopy. The at-home amyloid test from our partner site uses that staining principle on a finger-prick dried blood sample, and the report is ready within 1 day of the lab receiving the sample. It's informational data for you and your clinician, not a diagnosis.