A 64-year-old man has died on the Costa Blanca, eight days after getting his first shot of the AstraZeneca COVID vaccine.
The man suffered an aneurysm two days after the inoculation.
The condition is a weakening of an artery wall which in severe cases can cause fatal internal bleeding.
His family have blamed the vaccine dose for his death but there is so far no proven link between the jab and what happened.
He suffered from a chronic inflammatory lung disease known as MPOC.
The man was vaccinated in Elche in the late afternoon on April 6.
In the early morning he woke up with severe headaches and took some paracetamol as recommended.
Over the next two days he felt increasing pains across his body which culminated in him fainting at work and being sick.
An ambulance took him to Elche General Hospital with medics detecting internal bleeding, some two days after his vaccination.
He was transferred to Alicante General Hospital for further tests and treatment.
His bleeding began to stabilise but his condition then worsened and he died three days later.
Extremely rare cases of bloods clots have been detected among people who have taken the various brands of COVID vaccines around the world.
Earlier this month, use of the Johnson & Johnson vaccine was suspended in America and the European Union after six blood clot cases were detected in the United States out of seven million vaccine doses.