About 1,500 of the initial volunteers in a late-stage clinical trial of the Oxford-AstraZeneca COVID-19 vaccine were given the wrong dose, but weren't informed that a mistake had been made after the blunder was discovered, documents obtained by Reuters show.

Volunteers in AstraZeneca trial given wrong dose, documents reveal

After acknowledging a key mistake in its vaccine dosage, AstraZeneca said that "additional study" was to validate the efficacy of the vaccine. Watch: The British drugmaker had earlier said that average efficacy of the vaccine was 70 per cent.

AstraZeneca says COVID-19 vaccine need 'additional study'

AstraZeneca has paused an experimental vaccine for the coronavirus after the illness of a participant. The World Health Organization's (WHO) chief scientist said that is a “wake-up call” but should not discourage researchers.

Coronavirus vaccine: AstraZeneca pauses COVID-19 vaccine trial

The volunteer whose serious ailment halted clinical trials of a coronavirus vaccine candidate being developed by AstraZeneca and Oxford University

What do halted trials mean for the world?

After it "paused" its clinical trial over the vaccine this week, AstraZeneca's CEO Pascal Soriot said today that a vaccine was still possible by the "end of this year, early next year".

Could still have a vaccine by the end of the year, early next year: AstraZeneca CEO

AstraZeneca Covid-19 vaccine study is on a temporary hold after a participant falls ill. AstraZeneca didn't reveal any information about the possible side effect expect to call it 'a potentially unexplained illness'.

WION Fineprint: Oxford-Astrazeneca pause major trial for second time

AstraZeneca COVID-19 vaccine study paused after a participant falls ill in UK