Microbiologist Siouxsie Wiles says the Covid-19 vaccine candidate undergoing trials at Oxford University in England is the most promising of any of the current vaccine trials.
Scientists at Oxford have said their experimental vaccine has been shown to prompt a protective immune response against Covid-19 in hundreds of people who took it.
Dr Wiles said the successful trial of the drug should be taken with some caution, but that it is "really promising", and that a lot of people in the scientific community considered this vaccine to a be a front-runner.
"The strategy they are using is one that has been shown to work with other infectious diseases," Dr Wiles told TVNZ1's Breakfast.
"Of all of the ones in trials at the moment, this is probably the one that I'm most excited about."
The vaccine is being developed in partnership with drug company Astra Zeneca, which has already purchased 100 million doses of it, despite it not even being out of trials yet.
Dr Wiles said it is likely the company is "hedging its bets" and hoping that the vaccine will be successful.
Should the vaccine be approved for human use, it's likely that the people who need it most will get it first - like those more at risk from Covid-19, or those with compromised immune systems.
The vaccine is now in the third phase of its trials, which Dr Wiles said could last up to a year, but she said it's possible that the vaccine could be released earlier.
"The question will be, I guess, if it is showing it's effective in the early stages, then whether there's sort of permission given to essentially stop the trial early and start using the vaccine properly," she said.
"The companies involved are ramping up production in anticipation that it would work."