AstraZeneca has admitted for the first time in court documents that its Covid vaccine can cause a rare side effect, in an apparent about-turn that could pave the way for a multi-million pound legal payout.

The pharmaceutical giant is being sued in a class action over claims that its vaccine, developed with the University of Oxford, caused death and serious injury in dozens of cases.

Lawyers argue the vaccine produced a side effect which has had a devastating effect on a small number of families.

The first case was lodged last year by Jamie Scott, a father of two, who was left with a permanent brain injury after developing a blood clot and a bleed on the brain that has prevented him from working after he received the vaccine in April 2021. The hospital called his wife three times to tell her that her husband was going to die.

AstraZeneca is contesting the claims but has accepted, in a legal document submitted to the High Court in February, that its Covid vaccine “can, in very rare cases, cause TTS”.

TTS – which stands for Thrombosis with Thrombocytopenia Syndrome – causes people to have blood clots and a low blood platelet count.

Fifty-one cases have been lodged in the High Court, with victims and grieving relatives seeking damages estimated to be worth up to £100 million.

AstraZeneca’s admission – made in a legal defence to Mr Scott’s High Court claim – follows intense legal wrangling. It could lead to payouts if the drug firm accepts that the vaccine was the cause of serious illness and death in specific legal cases. The Government has pledged to underwrite AstraZeneca’s legal bills.