A new coronavirus vaccine which has safely triggered an immune response to the lethal infection in its first phase trial has been described as "encouraging".
The Beijing study has sent hopes rising around the world that a vaccine against the virus may be developed, although there is still a long road ahead.
Kingston Mills, Professor of Experimental Immunology in Trinity College Dublin, said: "The good news is that it is inducing the right kind of immune response."
He was commenting after details emerged of the first clinical trial of the experimental jab which was found to be safe and well-tolerated. "It is producing neutralising antibodies and it also looked at the T-cell response. Overall the response looks very good, but it is very early days," he said.
Phase two and three trials are needed yet.
Countries around the world are desperate for news on developments in the race to produce a vaccine and release populations from the devastating threat of the virus.
The new research, published in 'The Lancet' medical journal, revealed the findings after testing the vaccine on 108 healthy adults.
It demonstrated promising results after 28 days - the final results will be evaluated in six months' time.
Further trials are needed to tell whether the immune response it elicits effectively protects against Covid-19.
Prof Wei Chen from the Beijing Institute of Biotechnology in China, who is responsible for the study, said: "These results represent an important milestone.
"The trial demonstrates that a single dose of the new vaccine produces virus-specific antibodies and T-cells in 14 days, making it a potential candidate for further investigation.
"However, these results should be interpreted cautiously.
"The challenges in the development of a Covid-19 vaccine are unprecedented, and the ability to trigger these immune responses does not necessarily indicate that the vaccine will protect humans from Covid-19."
Prof Mills said the phase-two and phase-three trials of the vaccine would take many months.
Even if there was an effective vaccine, the challenge would be to produce it in the quantities needed to be delivered across many countries, he added.
These are the first published phase-one results - although other companies working on vaccines are also advancing in the various trial phases.
Asked about the phase-one results, chief medical officer Dr Tony Holohan said while the development of a vaccine against the virus was not a certainty, he remained hopeful.
There were still questions around "how strong the immunity might be and how long-lasting the immunity could be", he said.
In the US and UK, vaccines from Moderna and Oxford University have also shown promising early results.