Rit’s just Deadly blood clots linked to Covid-19 shots from Johnson & Johnson and AstraZeneca Plc were caused by an autoimmune reaction that some people are predisposed to, researchers have found, a discovery they say will shape the development of future vaccines.
Adenovirus-based vaccines, like the J&J and AstraZeneca shots that were later withdrawn from the market, contain a component that, in genetically susceptible people, can trigger the production of unusually structured antibodies against a protein involved in blood clotting. , scientists said Wednesday in a statement. letter to the New England Journal of Medicine. Researchers plan to identify the culprit and then attempt to remove it using genetic engineering.
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An extremely similar deleterious antibody response occurs in susceptible patients following infection with adenovirus, which often infect the airways and lead to cold-like symptoms, the study found. It is not known how many people may be susceptible to the complication, said Tom Gordon, head of immunology at Flinders University in South Australia, whose molecular research led to the meet.
The immune reaction associated with the vaccine is “a new disease,” he said in an interview. Hematologists and intensive care specialists will likely detect more cases as they become more familiar with the issue, he said.
“It’s a kind of autoimmunity where we know the trigger,” said immunologist James McCluskey, assistant vice-chancellor at the University of Melbourne, who was not involved in the research. “This is unusual. In most cases, we never manage to control the trigger.”
Vaccines withdrawn
Of the more than 18 million people who have received J&J’s single-dose vaccine, 60 cases of the clotting disorder have been reported and nine people have died, according to the Yale School of Medicine.
A small number of clot-related deaths linked to the AstraZeneca vaccine led to its withdrawal or restriction in Denmark, Norway and other countries in 2021. The complication occurred in about 2-3 people per 100,000 people vaccinated with the Astra vaccine under the age of 60 in Australia, where it has not been available since March 2023. The European Commission withdrew authorization to market the immunization in March 2024.
“AstraZeneca welcomes any further examination of the possible underlying mechanism of thrombosis with thrombocytopenia syndrome (TTS), as despite extensive research, we still do not understand the mechanism that may, in very rare cases, be a trigger for TTS ,” a spokesperson for the company said.
J&J also said it supports research that helps guide the development of safe and effective vaccines.
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“More data is needed to fully understand the potential factors that may be associated with this rare event, including its potential relationship to adeno and other viruses, to draw appropriate conclusions about the underlying pathogenesis,” the company said in an email.
Both shots played an important role in vaccination programs during the early stages of the pandemic. One analysis found that the Astra vaccine saved about 6.3 million lives in 2021.
The mRNA vaccines made by the Pfizer Inc.-BioNTech SE and Moderna Inc. partnership were later found to be more effective in protecting against Covid and have been updated to combat newer variants of the virus.
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