Explained: Can Covid vaccine cause rare side effect 'TTS'? What it is, and what AstraZeneca admitted in court

AstraZeneca, which developed a vaccine against COVID-19 in collaboration with the Oxford University in 2020, has admitted before the UK High Court that its vaccine doses can lead to a rare side effect known as Thrombosis with Thrombocytopenia Syndrome (TTS), reports said on April 29.

The admission by AstraZeneca does not cast doubt on all COVID-19 vaccines, but it brings under scanner the vaccine that was developed by it at a record pace amidst the pandemic period.

In India, the AstraZeneca vaccine was manufactured and sold as Covishield by the Pune-based Serum Institute of India (SII).

AstraZeneca, which is a British-Swedish pharmaceutical major, is facing a spree of lawsuits in the UK High Court, with petitioners linking the vaccine with cases of deaths and severe injuries. The claimants have cumulatively sought compensation of up to 100 million pounds.

One of the first complainants against AstraZeneca, Jamie Scott, alleged that he suffered a brain injury due to blood clots after being administered with the AstraZeneca vaccine in April 2021. He has claimed that he cannot work due to the brain injury, and the hospital where he was treated told his wife thrice that he will die.

What AstraZeneca said in court

The company has so far rejected the allegations that link its vaccine with cases of deaths or severe impairments. In response to the suit filed by Jamie Scott, AstraZeneca has challenged his claims, but admitted in one of its court documents in February that the vaccine, “in very rare cases, can lead to TTS.

The admission contradicts AstraZeneca’s earlier stand on Scott’s suit, when its lawyers had stated in 2023 that "we do not accept that TTS is caused by the vaccine at a generic level", reports pointed out.

What is TTS that is feared to be caused by the AstraZeneca vaccine?

Thrombosis with thrombocytopenia syndrome or TTS is a very rare syndrome. It occurs when a person has blood clots (thrombosis) together with a low platelet count (thrombocytopenia), explained Health Direct, a health advisory platform of the Australian government. It's also referred to as 'vaccine-induced immune thrombotic thrombocytopenia' (VITT).

“Thrombosis is the formation of a blood clot, which can reduce normal blood flow in an affected blood vessel, and Thrombocytopenia is a condition where there aren't enough platelets in the blood,” it said.

Platelets normally help the blood to clot (clump), which stops you from bleeding excessively (for example, if you cut yourself). The blood clots can occur in different parts of the body, including the brain, abdomen, lungs, limb veins and arteries.

Symptoms of TTS affecting the brain includ severe, persistent headache, blurred vision, difficulty speaking, drowsiness, seizures or confusion, according to Health Direct.

Meanwhile, the symptoms related to the disease that affect the rest of the body are as follows: difficulty in breathing, chest pain, leg swelling, persistent abdominal (stomach) pain and tiny blood spots under the skin.