Study: cause of fatal blood clots identified after coronavirus vaccinations with J&J and AstraZeneca vaccines

Scientists have found the cause of blood clots after vaccination against Covid-19 with drugs from Johnson & Johnson and AstraZeneca.

Rare but fatal side effects of blood clots associated with vaccines have been caused by an autoimmune reaction to which some people are genetically susceptible. About it, writes Time, according to a study published in The New England Journal of Medicine. Scientists believe that the study results will influence the development of future vaccines.

The findings suggest that adenovirus-based vaccines, such as J&J's and AstraZeneca's, contain a component that, in genetically susceptible people, can trigger the production of unusually structured antibodies against a protein involved in blood clotting. Researchers plan to identify this component and try to remove it using genetic engineering.

Tom Gordon, head of the department of immunology at Flinders University in South Australia, whose molecular research led to this important discovery, noted that hematologists and critical care specialists are likely to identify more cases of thrombosis risk through this component as they become more aware of this complication .

Of the approximately 18 million people who received the one-shot J&J vaccine, 60 experienced blood clots and nine died, according to the Yale School of Medicine.

Deaths linked to blood clots have led to the withdrawal or restriction of use of the AstraZeneca vaccine in several countries, including Denmark and Norway, in 2021. In Australia, complications occurred in 2-3 people per 100,000 vaccinated under 60 years of age, and the vaccine is no longer available from March 2023. The European Commission revoked marketing authorization for this vaccine in March 2024. A company representative said:

“AstraZeneca welcomes further investigation into the possible mechanism of thrombosis with thrombocytopenia syndrome (TTS) as, despite extensive investigation, we still do not understand the mechanism which in very rare cases may be a trigger for TTS.”

Johnson & Johnson also said it supports research to help develop safe and effective vaccines. Her email states:

“More data are needed to fully understand the potential factors that may be associated with this rare event, including its possible association with adenoviruses and other viruses, in order to draw appropriate conclusions about the basis of pathogenesis.”

Experts note that both vaccines played an important role in vaccination programs early in the pandemic. One study found that the AstraZeneca vaccine saved an estimated 6.3 million lives in 2021. Vaccinations against COVID-19 have saved more than 1.4 million lives in Europe, according to the World Health Organization.

AstraZeneca has begun the process of withdrawing its COVID-19 vaccine from sale. This decision was explained by the excess of updated drugs on the market.

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