One of the leading professors working on a coronavirus vaccine has said work to manufacture doses in Autumn is "still on track", with scientists now ramping up human trials.
From today, children and older adults are to be enrolled onto the University of Oxford's vaccination study - meaning more than 10,000 people are being tested.
The study is considered to be one of the frontrunners for developing a Covid-19 vaccine, and earlier this week a deal with pharmaceutical giant AstraZenica to manufacture millions of doses by September if trials prove successful.
But the government has repeatedly stressed there are no guarantees a vaccine will ever be found.
- Professor Andrew Pollard is leading the research into developing a vaccine:
Professor Andrew Pollard, from the University of Oxford, is leading the research into developing a vaccine.
He told ITV News: "What we're trying to do, as I think most vaccine developers are, is to move as quickly as possible while maintaining the integrity of trails and the safety of the products.
"The timelines for being able to do that are long.
"It can’t be done in a matter of weeks, it takes months, but we do remain on track if everything is aligned correctly to be able to have results and be able to manufacture the vaccine this autumn.
“But there remains uncertainties, which I've said right from the beginning. We’re in an unpredictable situation, but it’s entirely possible."
Human trials began in late April, initially involving about 1,000 healthy adults.
Scientists are now expanding the trials to include adults aged over 70, and a small number of children.
It is hoped that will give more information as to whether the vaccine can provide protection for the wider population.
Some experts have expressed worries that with the rate of transmission falling and the number of cases in the general population falling, it will be harder for scientists to evaluate if the vaccine is successful.
Some have predicted that finding a vaccine will likely take 12 to 18 months.
Professor Pollard said: "There is more of challenge when we have smaller numbers of cases in the population. There’s two ways of managing that; one is you just have a much larger trial."
He added: "The second is It may take longer, if you have very few cases you just have to wait longer."
Coronavirus: Everything you need to know: