Researchers analysed the results of the phase II of clinical trials, which were conducted on 560 healthy adults.
The prestigious scientific journal said the findings were “encouraging” because older individuals are at disproportionate risk of severe COVID-19.
The inoculation was found to be safe and well-tolerated.
New data from the critical phase III trial is expected soon, as analysts at Jefferies said on Tuesday after a discussion with the pharma giant’s chief financial officer Marc Dunoyer.
Interim results from the final stage of trials in the UK, Brazil and South Africa should come in “days to weeks”, as management already guided for figures to be released by year-end.
The firm is conducting studies on 30,000 people globally to assess the jab.
Meanwhile, a vaccine developed by China's Sinovac Biotech was found to develop a quick immune response in mid-stage trials on 700 people.
“The report on the AstraZeneca and University of Oxford vaccine was less likely to move the dial as, unlike the other major vaccine updates so far, there was no detail on its efficacy,” said AJ Bell investment director Russ Mould.
In fact, markets were focused on rising infections across Europe while the FTSE 100 firm remained flat at 8,168p.