AstraZeneca’s Covid vaccine linked to another rare blood disorder

Over a week after AstraZeneca announced a global withdrawal of its vaccine against coronavirus citing a slowdown in sales and availability of enough options in the market, new research has linked it to a rare disorder.

Researchers found that the AstraZeneca vaccine, sold in India under the brand name Covishield, is linked to a rare blood clotting disorder called Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT).

According to the scientists from Flinders University, Australia, who recently shared their study in the New England Journal of Medicine, VITT emerged in 2021 during the Covid-19 pandemic, particularly after the use of the Oxford-AstraZeneca vaccine, which is based on adenovirus vectors.

Scientists discovered that VITT is caused by a harmful blood autoantibody targeting a protein called platelet factor 4 (PF4). Separate research in 2023 revealed a similar, sometimes fatal disorder linked to natural adenovirus infections, such as the common cold, involving the same PF4 antibody.

An autoantibody is a type of antibody produced by the immune system that mistakenly targets and attacks the body’s own tissues, thinking they are foreign invaders. This can lead to autoimmune diseases, where the immune system harms healthy cells and tissues.

Affected patients often develop blood clots in unusual places like the brain or the abdomen. They also have high levels of a substance called D-dimer in their blood.

Flinders University researchers, Dr Jing Jing Wang and Professor Tom Gordon, previously identified a genetic risk factor related to the PF4 antibody in 2022.

Their recent collaboration with international researchers found that PF4 antibodies in both vaccine-related VITT and natural adenovirus infections share identical molecular signatures.

This new study, using a novel method developed at Flinders University, shows that a common factor in viruses and vaccines triggers these harmful antibodies.

The research suggests that the mechanisms of antibody production in these disorders are nearly identical and share similar genetic risk factors.

Professor Gordon explained that these findings have significant clinical implications. The lessons learnt from VITT can apply to rare blood clotting cases after natural adenovirus infections and can help improve vaccine safety.

SHOULD YOU BE WORRIED?

According to the American Society of Hematology, vaccine-induced immune thrombotic thrombocytopenia (VITT) occurs within 4 to 42 days of taking the Covid vaccine. Therefore, there’s no need to worry. Symptoms could include severe headache, visual changes, abdominal pain, nausea and vomiting, back pain, shortness of breath, leg pain or swelling and easy bruising or bleeding.