In a first, AstraZeneca admits its Covid vaccine can cause rare blood clots

British-Swedish pharma giant’s covid vaccine was widely administered in over 150 countries

Pharmaceutical giant AstraZeneca has admitted that its widely used Covid vaccine, branded Covishield, can cause rare side effects including blood clots and low platelet count.

Covishield was developed by the British-Swedish company in collaboration with Oxford University, UK, and produced by the Serum Institute of India. It was widely administered in over 150 countries, including Britain and India.

Some studies conducted during the pandemic found the vaccine was 60 to 80 per cent effective in protecting against the novel coronavirus.

However, research has since found that Covishield can cause some people to develop blood clots, which may prove fatal.

A class action lawsuit filed in the UK claimed that the vaccine led to deaths and severe injuries and sought damages up to £100m for about 50 victims.

One of the complainants alleged that the vaccine caused him a permanent brain injury after he developed a blood clot, preventing him from working.

While AstraZeneca has contested these claims, it admitted for the first time in one of the court documents that the vaccine can “in very rare cases, cause TTS”, or Thrombosis with Thrombocytopenia Syndrome, which is characterised by blood clots and a low blood platelet count in humans.

“It is admitted that the AZ vaccine can, in very rare cases, cause TTS. The causal mechanism is not known,” the company said in the court documents in February, The Telegraph reported.

“Further, TTS can also occur in the absence of the AZ vaccine (or any vaccine). Causation in any individual case will be a matter for expert evidence,” it added.

The admission by AstraZeneca runs counter to the company’s insistence in 2023 that it would “not accept that TTS is caused by the vaccine at a generic level”.

The World Health Organization confirmed that Covishield can have life-threatening side effects. “A very rare adverse event called Thrombosis with Thrombocytopenia Syndrome, involving unusual and severe blood clotting events associated with low platelet counts, has been reported after vaccination with this vaccine.”

According to the Council for International Organizations of Medical Sciences, “very rare” side effects are those reported in less than 1 in 10,000 cases.

“In countries with ongoing SARS-CoV-2 transmission, the benefit of vaccination in protecting against COVID-19 far outweighs the risks,” the WHO added.