The vaccine, called AZD1222 and under development by AstraZeneca and scientists at Oxford, did not prompt any serious side effects and elicited antibody and T-cell immune responses, according to trial results published in The Lancet medical journal. The strongest response was seen in people who received two doses.

“We hope this means the immune system will remember the virus, so that our vaccine will protect people for an extended period,” study lead author Andrew Pollard of the University of Oxford said.

“However, we need more research before we can confirm the vaccine effectively protects against SARS-CoV-2 (COVID-19) infection, and for how long any protection lasts.”

AstraZeneca’s is among the leading vaccine candidates against COVID-19, that has claimed more than 600,000 lives worldwide, alongside others in mid and late-stage trials.

AstraZeneca has signed agreements with governments around the world to supply the vaccine should it prove effective and gain regulatory approval.

The UK Government has already signed a deal to secure 100 million doses of the vaccine while the US has a contract for 300 million of the initial 1 billion doses produced.

Australia’s Deputy Chief Medical Officer Nick Coatsworth said safety and effectiveness would be key to finding a suitable drug.

“It looks very encouraging and I know Professor Andy Pollard and his group of researchers there, they are absolutely world-class,” he told ABC television on Tuesday.

The vaccine is intended to induce antibody and T cell responses so it can attack the virus and infected cells.

“They’re the two parts of the immune system that will work in concert to protect against COVID-19,” Dr Coatsworth said.

“So what we’re actually seeing is that those two elements of the immune system are boosted by the vaccine.”

He said the next step would be to see the boosted immune responses translate into protection from coronavirus.

British Prime Minister Boris Johnson said the announcement was “very positive news”, but also warned there are still further trials to take place.

“There are no guarantees, we’re not there yet & further trials will be necessary — but this is an important step in the right direction,” he tweeted.

Researchers also cautioned that the project was still at an early stage.

“There is still much work to be done before we can confirm if our vaccine will help manage the COVID-19 pandemic,” vaccine developer Sarah Gilbert said.

“We still do not know how strong an immune response we need to provoke to effectively protect against SARS-CoV-2 infection,” she said, adding researchers needed to learn more about COVID-19 and continue late-stage trials which have already commenced.

The Australian stock market was poised to rise in early trading, after promising results for possible coronavirus vaccines helped Wall Street end higher.

The Australian SPI 200 futures contract was up by 42.0 points, or 0.70 per cent, to 6012.0 points at 0800 AEST on Tuesday.

Overnight, US markets closed higher after drugs from AstraZenica, CanSino Biologics, and a partnership between Pfizer and German biotech firm BioNTech were safely administered and induced immune responses.

The drug results come after United States’ deaths from the virus passed the 140,000 mark over the weekend and cases continued to rise in 42 of 50 states.