A husband said his wife died a "hero" after a coroner ruled rare complications from the AstraZeneca vaccine caused her death.
Mother of two Michelle Barlow, 51, from Orrell, near Wigan, Greater Manchester, died 16 days after having the jab.
A civil servant for 34 years with the Department for Work and Pensions, Mrs Barlow was admitted to hospital after falling ill.
Her inquest heard she developed "unsurvivable" blood clots.
While doctors noted her recent vaccination, and emerging knowledge about bad reactions in some patients, they persisted with a diagnosis of a gastro infection, Bolton Coroner's Court heard.
One of her sons even searched online for the symptoms his mother was suffering, and it showed how other doctors were saving the lives of people with similar complications.
But three days after being admitted to Wigan Infirmary, Mrs Barlow died from blood clots as a result of "rare complications" of the Covid-19 vaccination, the inquest heard.
Timothy Brennand, senior coroner for Greater Manchester West, ruled, "The deceased died as the consequences of the unrecognised, rare complications of a recently administered elective and necessary Covid-19 vaccination."
Her multiple organ failure caused by the blood clots was as a result of vaccine-induced immune thrombotic thrombocytopenia (VITT) a condition not recognised at the time of her death, the inquest heard.
Mr Brennand said there may have been some "sub-optimal care" and "confirmation bias" among medics in persisting with their initial wrong diagnosis.
Outside court Mrs Barlow's husband, Ian, a retired factory worker, said he felt "relief" that the vaccine's role in her death had been recognised.
He said the family felt stonewalled by public health officials when he raised his concerns about the vaccine.
The family is calling for a judicial review of the vaccine rollout.
Earlier the inquest heard Mrs Barlow, originally from Portsmouth, went to a mass vaccination centre at Robin Park, Wigan and was given the AstraZeneca jab on March 7.
She slowly began to suffer "side effects" of flu-like symptoms over the next couple of weeks.
On March 19 she first went to Wigan Infirmary but her husband said she felt "fobbed off" and was discharged.
The next day she went to the A&E department of the hospital and was admitted, with medics first suspecting a gastro-enteritis infection.
Her husband and family were unable to be with her at the hospital due to Covid restrictions, and on March 22 Mr Barlow got a phone call from a nurse telling him to get to the hospital as soon as possible.
Son Matthew Barlow said that while his mother was in hospital he clicked on an internet link showing how a professor in Norway had "saved five lives" of patients suffering the same symptoms as his mother.
He added: "If I can do that, why can't the doctors and nurses who were treating my mother? Just go on Google."
The coroner said he could not say whether Mrs Barlow would have lived if doctors had recognised sooner that the bad reaction to the vaccine was casing her illness.
Pathologist Dr Naveen Sharma said the Medicines and Healthcare products Regulatory Agency (MHRA) had this month produced guidance suggesting a possible link between the AstraZeneca vaccine and the "very rare" side effect of blood clots.
He said 425 cases of major blood clots had been identified in people who had taken the AstraZeneca vaccine and said this represented rare but very clearly recognised potential complications.
Of the 425 cases, 215 in women and 206 in men, 154 cases related to blood clots in the head and 271 other parts of the body.
Of the 425 cases, the ages ranged from 18 to 93, with 101 cases in the 50 to 59 age range, 19 of whom were among the 73 fatal cases in total.
He said currently 24.8 million people had been given the first dose of the AstraZeneca vaccine and 24.1 million people had been double-jabbed with it.
Dr Peter Kreppel, Mrs Barlow's GP, who referred her to hospital, said he still would have recommended her taking the vaccine, as the risk of thrombosis was 100 times greater without the vaccine than when having taken it.
Dr Mian Ahmed, consultant at Wigan Infirmary, said if the same situation arose now, he would prescribe haemoglobin, blood thinners and CT scans sooner to the patient.
Surgeon Dr Marius Paraoan told the hearing that once he looked at Mrs Barlow's CT scan he concluded the blood clots were not treatable with surgery and "not compatible with survival"