The World Health Organisation has warned we shouldn't expect to see vaccine for 12 months or more.
Scientists across the world have been racing to find a virus - with experts saying it is the "only tool" that can help curb the spread of COVID-19.
However, some scientists are more hopeful in saying they are 80% sure a vaccine could be ready by September.
Sarah Gilbert, a professor of vaccinology at Oxford University, says she is "80% confident" that a jab being developed by her team will be proved effective by the autumn.
The Times reports that human trials are set to begin on the vaccine in a fortnight, making it one of the most promising efforts in the world.
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The UK government has also indicated that, if results look positive, it is prepared to fund millions of doses in advance.
This means that if the tests are successful, an immunisation against Covid-19 would be widely available to the public immediately.
With medical experts fearing that lifting lockdown measures will lead to a fresh surge in infections, a return to normal life relies heavily on finding a vaccine that works.
Although it has been estimated this will take 18 months, Professor Gilbert has said that in a best-case scenario her team could have one ready by September.
She had previously said she hoped it could be developed by the end of the year.
"I think there's a high chance that it will work based on other things that we have done with this type of vaccine," she said.
"It's not just a hunch and as every week goes by we have more data to look at. I would go for 80 percent, that's my personal view."
However, she also warned that "nobody can promise it's going to work."
Prof Gilbert, who has been working seven days a week to put the vaccine through development stages, added that her researchers will need to trial it in a country with a high rate of transmission to get quick results.
China has approved early-stage human tests of two experimental vaccines to combat the new coronavirus as the country where the virus was first detected battles to contain imported cases, especially from Russia.
Russia has become China's largest source of imported cases, with a total of 409 infections originating in the northern neighbour.
Chinese people there should stay put and not return home, the state-owned Global Times said in an editorial Tuesday.
"Chinese people have watched Russia become a severely affected country ... This should sound the alarm: China must strictly prevent the inflow of cases and avoid a second outbreak," said the paper, which is run by the Communist Party's People's Daily.
