AstraZeneca's Covid-19 Vaccine Can Cause A Second 'Rare' Blood Clotting Disorder?What Research Says
Within a little over a week since the UK-based pharmaceutical giant AstraZeneca announced a global roll back of its Covid-19 vaccine citing commercial reasons amid a row over the vaccine causing Thrombosis Thrombocytopenia Syndrome (TTS), fresh research has identified its potential to cause another rare blood clotting disorder called Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT).
Recently, Astrazeneca's vaccine, globally known as Vaxzevria, or Covishield in India, came under scrutiny as the pharma company admitted in court documents that in 'very rare cases' Covishield could cause a blood clot-related disorder called Thrombosis Thrombocytopenia Syndrome (TTS) .
What is VITT?According to the scientists from Australia's Flinders University, VITT emerged in 2021 during the Covid-19 pandemic following widespread usage of the Oxford-AstraZeneca vaccine, which is based on adenovirus vectors. The blood clotting related disorder, as per research, occurs within 4 to 42 days of taking the Covid vaccine.
VITT: Symptoms, cause of concernAccording to the American Society of Hematology, the symptoms could include the following:
AstraZeneca Covid-19 Vaccine Linked To Fatal Blood Clotting Disorder
AstraZeneca's Covid-19 vaccine is associated with another rare but fatal blood clotting disorder, according to new findings published in the New England Journal of Medicine. These results have significant implications for enhancing vaccine safety (1✔ ✔Trusted SourceAstraZeneca vaccine: Blood clots are "extremely rare" and benefits outweigh risks, regulators concludeGo to source). The British-Swedish pharmaceutical company AstraZeneca, in collaboration with Oxford University, acknowledged that their Covid vaccine can, in extremely rare cases, cause Thrombotic Thrombocytopenic Syndrome (TTS). Researchers recently found that the vaccine increases the risk of vaccine-induced immune thrombocytopenia and thrombosis (VITT), a rare and fatal clotting disorder. 'Did You Know?AstraZeneca's Covid-19 vaccine can, in very rare cases, cause a fatal blood clotting disorder. #covid #vaccine #covishield #medindia' Although VITT was not previously known, it emerged during the Covid-19 pandemic in 2021 following the use of the adenovirus vector-based Oxford-AstraZeneca vaccine, marketed as Covishield in India and Vaxzevria in Europe. The disorder is caused by an unusually harmful blood autoantibody targeting a protein called platelet factor 4 (PF4).In 2023, researchers from Canada, North America, Germany, and Italy reported a similar disorder with the same PF4 antibody that was fatal in some instances after natural adenovirus infections (common cold). Recent research by Flinders University in Australia and international experts revealed that the PF4 antibodies in both adenovirus infection-associated VITT and the classic adenoviral vector VITT share identical molecular signatures.
Professor Tom Gordon from Flinders University noted that the pathways for producing lethal antibodies in these disorders are virtually identical and likely share genetic risk factors. He emphasized that the findings have crucial clinical implications, suggesting that insights from VITT could apply to rare cases of blood clotting following adenovirus infections and inform future vaccine development.
In 2022, the same research team decoded the molecular structure of the PF4 antibody and identified a genetic risk factor. Their recent findings further underscore the importance of improving vaccine safety.AstraZeneca had previously admitted in a legal document to the High Court in February that their Covid vaccine could, in very rare instances, cause TTS. This rare side effect, linked to at least 81 deaths in the UK and numerous serious injuries, prompted the company to withdraw the vaccine's marketing authorization from Europe and other global markets.
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Reference:What Is VITT, The Other Blood Clotting Condition Linked To AstraZeneca's COVID-19 Vaccine?
British-Swedish pharma giant AstraZeneca has remained in the headlines after reports surfaced that it admitted its COVID-19 vaccine can cause a rare side effect of blood clotting. Now, Australian researchers have found a link between vaccine-induced immune thrombocytopenia and thrombosis (VITT), a rare complication associated with AstraZeneca's COVID-19 jabs, and an uncommon but potentially fatal blood disease contracted by some who had a cold.
According to Adelaide's Flinders University, the antibodies from VITT and an adenovirus VITT-like disorder share nearly identical molecular signatures or fingerprints.
"These findings, using a completely new approach for targeting blood antibodies developed at Flinders University, indicate a common triggering factor on virus and vaccine structures that initiates the pathological PF4 antibodies," the university's Professor Tom Gordon was quoted as saying by 9news.Com.Au.
Researchers said these findings will have implications for vaccine development and safety.
What is VITT? Is it different from TTS? How is it linked to AstraZeneca 's COVID-19 vaccine? Let's take a closer look.
What is VITT?
VITT is a rare condition found in some people who got adenoviral vector COVID-19 vaccines such as AstraZeneca's Vaxzevria and the Johnson & Johnson's Janssen shots.
The adverse effect led to blood clots and low platelet count in healthy young adults.
VITT is marked by "venous or arterial thrombosis, particularly at unusual sites including cerebral sinus venous thrombosis (CSVT)/splanchnic thrombosis; mild to severe thrombocytopenia (low platelet count); and positive PF4-heparin ELISA ("HIT" ELISA)", according to American Society of Hematology.
HIT stands for Heparin-induced thrombocytopenia which is an immune complication that can occur in patients exposed to heparin products.
Thrombosis refers to a blood clot within blood vessels that restricts the flow of the red-hued body fluid.
VITT leads to blood clots and low platelet count in healthy young adults. Pixabay (Representational Image)The symptoms of VITT include persistent headaches, shortness of breath, abdominal pain, easy bruising or bleeding, nausea and vomiting.
People who have VITT, their immune response gets compromised and they make antibodies that can stick to one of the body's own proteins called platelet factor 4 (PF4), as per The Conversation.
TTS and VITT
AstraZeneca has accepted in court documents in the United Kingdom that its COVID-19 vaccine, in rare cases, can cause Thrombosis with Thrombocytopenia Syndrome (TTS).
TTS is a broader category that can be triggered by vaccine or it can be non-immune mediated. As per ScienceDirect, "VITT can be considered as one of several entities that fall under the umbrella of immune-mediated TTS".
A 2022 study in Lancet Global Health revealed that AstraZeneca had reported rates of 8.1 TTS cases per million who got the first dose of its COVID-19 vaccine and 2.3 cases per million after people got the second jab. The highest number of these cases were found in Nordic countries – 17.6 per million doses – and the lowest in Asian nations – 0.2 per million doses.
A nurse displays a vial of Covishield, during the coronavirus disease (COVID-19) vaccination campaign, at a medical centre in Mumbai, on 16 January 2021. Reuters File PhotoIn India, at least one young woman is believed to have died from VITT after taking Covishield .
Rithaika Sri Omtri, 18, got the first dose of Covishield in May 2021 in Hyderabad. As per a Scroll report, within five days of being vaccinated, she experienced a prickling sensation in her fingers and, later, a high fever.
As her fever did not subside for a few days, a doctor suggested her a blood test which revealed her platelets had dropped to a dangerous low of 40,000 per cubic millimetre, compared to a normal range between 1.5 lakh and 4 lakh.
Over 10 days later, Rithaika started vomiting and could not walk. An MRI scan of her brain showed that she had multiple blood clots and a haemorrhage in the right frontal region, Scroll reported.
Despite efforts to save her, she was declared brain dead, two weeks after her vaccination.
Rithaika had suffered a "vaccine-induced (immune) thrombotic thrombocytopenia", Scroll reported.
AstraZeneca under scanner
The pharma giant has been under scrutiny since its admission came to light. People who took its COVID-19 vaccine started questioning its safety. However, experts said the side effects appeared within the first few weeks of taking the vaccine and there was no need to worry now.
Recently, AstraZeneca said its COVID-19 vaccine, which was manufactured by the Serum Institute of India (SII) and sold as Covishield in India, has been removed from the markets for commercial reasons.
With inputs from agencies
