May 01, 2024 05:56 AM IST
The AstraZeneca vaccine Vaxzevria was administered in India under the brand name Covishield and manufactured by the Serum Institute of India (SII)
Experts stressed that recent disclosure by drugs multinational AstraZeneca in a London court that the Covishield vaccine can cause blood clots in “very rare cases” is not something that was previously unknown, adding that almost everyone who got the shot is in no danger of this extremely rare side-effect.
“The association of adenovirus vectored vaccines with TTS (Thrombosis with Thrombocytopenia Syndrome) was identified by WHO (World Health Organization) in April 2021. This is a rare side effect, and occurs within four and 20 days after vaccination. When recognised, there is a clear protocol for treatment,” said vaccine scientist Dr Gagandeep Kang. “Since most people were vaccinated years ago, there is no cause for concern at this time.”
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The AstraZeneca vaccine Vaxzevria, which was administered in India under the brand name Covishield and manufactured by the Serum Institute of India (SII), was the primary vaccine used in India’s immunisation programme to deal with the Covid-19 pandemic, accounting for eight out of every 10 shots delivered in the country.
“The furore about Covishield is quite surprising. Nothing new in terms of information and more importantly nothing in that information that should make us fearful of vaccines,” Anurag Agrawal, dean of biosciences and health research at Ashoka University, said in a post on X (formerly Twitter).
The Daily Telegraph in the UK reported that in a legal document submitted to the high court in London in February for a class action lawsuit, AstraZeneca admitted its vaccine developed in partnership with the Oxford university to protect against Covid-19 may cause thrombosis with TTS in “very rare cases”.
TTS is a rare condition when thrombosis (formation of clots in blood vessels) and thrombocytopenia (low platelet count) occurs. According to the European Medicine Agency on the side effects of the Vaxzevria vaccine, TTS and Guillain-Barré syndrome (a neurological disorder in which the body’s immune system damages nerve cells) may affect up to one in 10,000 people.
“A very small number of cases of immune thrombocytopenia (a condition in which the immune system mistakenly targets blood platelets, reducing their levels and affecting normal blood clotting) and cerebrovascular venous and sinus thrombosis (formation of blood clots in the vessels draining blood from the brain) have also occurred,” the European drugs regulator had said.
Vaxzevria is made up of another virus of the adenovirus family that has been modified to contain the gene for making a protein from SARS-CoV-2, the virus that causes coronavirus disease.
AstraZeneca is fighting a class action lawsuit seeking damages worth nearly 100 million British pounds, according to local media reports. A person named Jamie Scott filed the first case in 2023. Scott was left with a permanent brain injury after developing a blood clot and a bleed on the brain since April 2021, when he received the vaccine.
No vaccine is without risk, but benefits outweigh risks in the one that are approved, experts said. “Vaccine safety is important, and is a primary focus of study for all vaccines. But it is always important to balance benefit and risk, and all licensed vaccines deliver much more benefit and very small risk,” Dr Kang said. “Nonetheless, still important to monitor so that the condition is quickly recognised and appropriate management can be made available early.”
- ABOUT THE AUTHOR
Rhythma Kaul works as an assistant editor at Hindustan Times. She covers health and related topics, including ministry of health and family welfare, government of India.
