Global tests, carried out in the UK, US, South Africa, England, Russia and Brazil, paused last week after a participant in the UK registered adverse effects.
But the FTSE 100-listed group said they are now underway again in the UK after the Medicines Health Regulatory Authority advised that it was safe to do so.
Oxford University Professor Andrew Pollard said in August that data could be put before regulators as early as this year. but ensuring safety and efficacy is paramount.
AstraZeneca has sourced capacity for 2bn doses.