AstraZeneca coronavirus vaccine, which was sold in India as Covishield, is linked to a rare blood clotting disorder called Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT), researchers have found.
Pharmaceutical company AstraZeneca earlier this month had announced the worldwide withdrawal of its Covid-19 vaccines. Although "surplus of available updated vaccines" that target new variants of the virus was cited as the reason for the withdrawal, the decision came days after the company acknowledged in court papers that the vaccine carried serious side effects, known as thrombosis with thrombocytopenia, or TTS, in some people. This also follows the AstraZeneca's decision to withdraw its European Union marketing authorisation. On May 6, Monday, the European Medicines Agency issued a notice that the vaccine is no longer authorised for use.
It was scientists of South Australia's Flinders University that revealed in a study VITT emerged in 2021 during the Covid-19 pandemic, particularly after the use of the Oxford-AstraZeneca vaccine. The jab was based on adenovirus vectors, India Today said in a report.
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According to the researchers, VITT is caused by a harmful blood autoantibody targeting a protein called platelet factor 4 (PF4), the report said. Another research last year had revealed a similar fatal disorder linked to natural adenovirus infections involving the same PF4 antibody.
PF4 antibodies in vaccine-related VITT and natural adenovirus infections reportedly share identical molecular signatures.
Understanding "autoantibody"
US-based National Cancer Institute describes "autoantibody" as an antibody produced by the immune system that attacks the body's own proteins. Autoantibodies can directly destroy cells that have substances on them or can make it easier for other white blood cells to destroy them.
This can cause to autoimmune diseases, where the immune system harms healthy cells and tissues. Affected people are likely to develop blood clots in unusual places including the brain, India Today said. The patients may also have high levels of a substance called D-dimer in their blood, the report said.
The new study reportedly found that a common factor in viruses and vaccines triggers these harmful antibodies.
However, VITT is likely to occur four to forty-two days after taking the vaccine. As people are no longer taking the vaccine, the study offers vaccinated people no reason to bother, the report added.
