AstraZeneca, for the first time, admitted in its court documents that its Covid vaccine, sold globally under the brand names Covishield and Vaxzevria among others, can cause rare side effects.

As per reports, the admission was made in a legal document submitted to the UK High Court in February.

The pharmaceutical company is being sued in a class action that its vaccine against Covid-19, developed with the University of Oxford, caused death and serious injury, including TTS — Thrombosis with Thrombocytopenia Syndrome — which causes people to have blood clots and a low blood platelet count.

51 cases have been lodged in the UK High Court, with victims and grieving relatives seeking damages estimated to be worth up to £100 million, the reports said.

The company stated in the document that a rare side effect known as Thrombosis with Thrombocytopenia Syndrome (TTS) can happen even if there is no vaccination, adding that expert testimony will be required to determine causation in every individual case. It said, “It is admitted that the AZ vaccine can, in very rare cases, cause TTS. The causal mechanism is not known.”

AstraZeneca, in collaboration with The University of Oxford, had developed AZD1222 vaccine after the outbreak of the coronavirus in 2020. In India, it was manufactured and supplied under the name “Covishield” by Serum Institute of India (SII) through a licence from the university and the Swedish-British drugmaker.