What is VITT? AstraZeneca COVID-19 Vaccine Linked to Rare Fatal Blood Clotting Disorder

Pharmaceutical giant AstraZeneca was in the midst of a controversy in early May this year, when they voluntarily withdrew its vaccine for the Coronavirus 2019 (COVID-19) from Europe and other international markets. Studies revealed that the AstraZeneca COVID-19 vaccine was found to raise the risk of vaccine-induced immune thrombocytopenia and thrombosis (VITT).

The AstraZeneca COVID-19 vaccine was developed in collaboration with Oxford University. Most people in India were administered the Covishield vaccine during the pandemic. Covishield, by Serum Institute of India, is another name for the AstraZeneca COVID-19 vaccine. It was sold as Vaxzevria in Europe.

What is VITT?

VITT is a rare condition that leads to the clotting of blood. The condition may develop among those who have been  administered the AstraZeneca COVID-19 vaccine. Although VITT is an existing disease, experts say it is a new disease following the adenovirus vector-based Oxford/AstraZeneca vaccine. 

Is VITT the same as TTS?

Earlier, the AstraZeneca COVID-19 vaccine was linked to a similar blood-clotting condition called thrombosis with thrombocytopenia syndrome (TTS). AstraZeneca "accepted, in a legal document submitted to the High Court in February, that its Covid vaccine 'can, in very rare cases, cause Thrombotic Thrombocytopenic Syndrome (TTS)'."

TTS is a rare side effect of the COVID-19 vaccine that may cause blood clots and a low blood platelet count. At least 81 people have died in the UK of TTS and several hundreds ended up with serious injuries as a result of the rare blood clots.

As per reports about the syndrome, TTS is another name for VITT. 

What does the new research on AstraZeneca COVID-19 vaccine say?

The AstraZeneca COVID-19 vaccine was claimed to have an efficacy of 72 per cent against symptomatic SARS-CoV-2 (COVID-19) infection. However, its side effects such as VITT or TTS are known to be life-threatening. A new study on the British-Swedish pharma giant’s COVID-19 vaccine, published in the New England Journal of Medicine, reportedly said that the reason for VITT was an "unusually dangerous blood autoantibody directed against a protein termed platelet factor 4 (or PF4)".

In an earlier research in 2023, scientists from Canada, North America, Germany and Italy revealed an identical disorder with the same PF4 antibody that was found to be fatal in certain cases even after natural adenovirus (common cold) infection. In a 2024 research, Flinders University, Australia along with other international scientists have found that the PF4 antibodies in the adenovirus infection-associated VITT as well as the classic adenoviral vector VITT had identical molecular fingerprints.

Professor Tom Gordon from Flinders University has been quoted by IANS as saying, "The pathways of lethal antibody production in these disorders must be virtually identical and have similar genetic risk factors." He noted that the findings have the “important clinical implication that lessons learned from VITT are applicable to rare cases of blood clotting after adenovirus (a common cold) infections, as well as having implications for vaccine development".

In 2022, the team had "cracked the molecular code of the PF4 antibody and identified a genetic risk factor", he revealed.