COVI SHIELD - SCI &
TECH
News: AstraZeneca acknowledges its
covid vaccine, Covishield, can lead to rare blood clot side effects
What's in the news?
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AstraZeneca, the company that makes the Covishield
vaccine for Covid-19 pandemic, has admitted the inoculation has potential side
effects.
Key takeaways:
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The company's admission, presented in a legal
document before the High Court of Justice in London, conveys that the Covid
vaccine can in extremely rare cases induce Thrombosis with Thrombocytopenia
Syndrome (TTS).
Thrombosis with
Thrombocytopenia Syndrome (TTS):
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TTS is a rare
condition characterized by the formation of blood clots (thrombosis) in
blood vessels and a low number of blood platelets (thrombocytopenia).
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It has been observed as an extremely rare adverse
effect associated with certain COVID-19 vaccines, notably those that use
adenovirus vectors, like the Covishield.
○
Adenovirus vectors are non-enveloped,
double-stranded DNA viruses that are commonly used for gene therapy,
vaccination, and cancer gene therapy.
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They are considered the most efficient gene
delivery vehicles due to their safety profile and expression.
Mechanism:
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The exact mechanism by which TTS occurs following
vaccination with Covishield is not fully understood.
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However, it is hypothesised that the vaccine may
trigger an immune response that leads to platelet activation and the formation
of blood clots.
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This is similar to autoimmune heparin-induced thrombocytopenia.
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Heparin is a well-known and commonly used
anticoagulant which has antithrombotic properties.
Symptoms:
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A range of symptoms are associated with TTS,
including breathlessness, pain in the chest or limbs, pinhead-size red spots or
bruising of the skin in an area beyond the injection site, headaches, numbness
in body parts, etc.
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TTS could mean a restriction in the flow of blood
due to clotting.
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Complications depend on where the thrombosis is
located. The most serious problems include stroke, heart attack, and serious
breathing problems.
Vulnerables:
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Certain factors might predispose individuals to
this condition, such as age, gender (more common in younger women), and
possibly genetic factors.
Concerns in India:
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India has already inoculated millions of people who have been administered Covishield, and this can result in reasons to
be worried about by the society as well as the medical association.
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Indian authorities have been making an emphasis
that the vaccine is secure together with advantages outnumbering risks.
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However, some experts have called for increased
vigilance and monitoring for any adverse effects.
Go back to basics:
Covishield:
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In 2020, amid the Covid-19 outbreak, the United Kingdom (UK) pharmaceutical firm
collaborated with the University of Oxford to develop the AZD1222 vaccine.
Covishield in India:
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In India, the vaccine produced by AstraZeneca was
marketed under the brand name Covishield, manufactured by the Serum Institute of India (SII) in Pune.
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India started administering the vaccines on January 16, 2021.
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Considering the total number of doses that had been
administered since then, the number of potential thromboembolic events worked
out to 0.61 cases per million doses.
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The Union Health Ministry said that Covishield
continues to have a definite positive benefit-risk profile with tremendous
potential to prevent infections and reduce deaths due to Covid-19.
AstraZeneca Vaccine in
Other Countries:
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In March 2021, many European countries such as France, Germany, Italy, Netherlands,
etc. temporarily paused the use of the AstraZeneca vaccine after a few cases of
blood clotting were reported.
Observations made by
WHO:
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Later in April 2021, the World Health Organisation
(WHO) said TTS was being reported in some cases after vaccinations with
Covishield.
● However, the WHO had added, based on latest available data, the risk of TTS with Covishield vaccines appears to be very low.