Study Debunks Vaccine-microclot Link, Confirms Elevated Clots in Long Covid Patients
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A recent study published in the Journal of Medical Virology is being misrepresented online, with claims falsely linking amyloid microclots to Covid-19 vaccines. The research actually demonstrates a substantially higher presence of these microclots in individuals suffering from long Covid, a finding consistent with prior research conducted before the availability of vaccines.
The Rise of Misinformation
The study, published in October 2025, revealed that people experiencing long Covid exhibit a considerable quantity of amyloid microclots – small blood clots composed of proteins the body struggles to eliminate – in their blood.however, this finding has been distorted on social media, with some users alleging the microclots are a result of vaccination, citing the fact that 95.5% of the 98 study participants had received a Covid-19 vaccine.
This misinformation extends to the propagation of another debunked claim circulating in anti-vaccine circles: that “white clots” observed during autopsies are caused by messenger RNA (mRNA) vaccines. These interpretations, experts emphasize, are entirely unfounded and lack any scientific basis.
Microclots and Long Covid: What the Science Shows
According to researchers, amyloid microclots are even found in small quantities in healthy individuals. Importantly, previous research had already established the presence of these clots in long Covid patients prior to the rollout of Covid-19 vaccines. “Their presence thus has no link with vaccination,” researchers state.
The study’s design did not allow for a comparison between vaccinated and unvaccinated individuals. Researchers did not analyze the vaccination status of participants as a factor, and therefore did not attempt to establish a correlation between vaccination and the presence of microclots.
The high percentage of vaccinated participants – 45 out of 50 in the long Covid group and 38 out of 38 in the healthy control group – simply reflects the vaccination rates in France and South Africa, where the study was conducted, during 2024. By the end of 2022, 83% of adults in mainland France had completed their Covid-19 vaccination schedule, according to the Directorate of Research, Studies, Evaluation and Statistics (Drees). [3] In South Africa, 51.5% of adults had received at least one dose by April 2023, according to the country’s Ministry of Health. [4] These figures demonstrate the context of the study population and do not imply a causal relationship with vaccination.
Understanding the Biological Mechanisms
The scientists’ primary goal was to better understand the physiological processes occurring in individuals with long Covid, not to investigate vaccine-related effects.Their research revealed that long Covid patients have significantly more amyloid microclots in their blood – on average,19 times more than healthy individuals,and often larger in size.
These microclots pose a health risk because the body has difficulty clearing them, potentially blocking blood flow in small vessels and reducing oxygen supply to tissues.This could explain common long Covid symptoms such as microthromboses, fatigue, pain, and difficulty concentrating.
The study also identified that these microclots are reinforced by “neutrophil extracellular traps” – a mixture of DNA and enzymes normally used to neutralize microbes.However, when these traps form in excessive quantities due to inflammation, they attach to microclots, making them more resistant and perpetuating
Reference: Bril, F., et al. (2021). cerebral venous thrombosis and portal vein thrombosis: A retrospective cohort study of 537,913 COVID-19 cases. EClinicalMedicine, 39, 101061. doi: 10.1016/j.eclinm.2021.101061. PMID: 34368663; PMCID: PMC8324974.
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