Health Minister Robin Swann has said that vaccination of at risk sections of the community could begin within weeks as he urged people to be positive for the future.
A vaccine being produced by US pharmaceutical giant Pfizer and German company BioNtech has proved more than 90% effective during testing in preventing Covid-19 among those without evidence of prior infection.
First Minister Arlene Foster said the news was "significant", and it has also been welcomed by Queen's University virologist Dr Connor Bamford as a major breakthrough in the treatment of the virus.
While warning the public not to be complacent despite the progress towards mass vaccination in 2021, Mr Swann said: "We have been waiting a long time for positive news. While there are very important regulatory and safety assurance hurdles to still be cleared, today represents a step forward.
"While there are no guarantees, there is a possibility that vaccination of at risk sections of our community could begin by the end of this year.
Positive: Robin Swann says the announcement is a major step forward
"However, I would appeal to everyone not to let down their guard just because there is some light at the end of this very long tunnel. It will likely be well into 2021 before a vaccine is generally available to the population, not least because mass global vaccination is a huge logistical challenge.
"As I have said before, we are in for a hard slog this winter in terms of intense pressures on our health service and unavoidable restrictions on our daily lives.
"We all have to redouble our efforts, continue limiting our contacts and keeping our distance from each other, wear face coverings when required, and keep washing our hands.
"But let's be positive about the future. The incredible progress to date on developing a vaccine, together with planned mass testing and improved treatments, means we can look towards next spring with some hope.
"Pessimists keep telling us we will be locked into endless stop-start cycles of restrictions. I have faith that they will be proved wrong."
Mrs Foster said the breakthrough showed that "the fight of common humanity against Covid is making significant strides forward".
"Great news from the vaccine trials," she said.
"This is much-needed hope. Our thanks to all those working on vaccine research."
Sinn Fein MLA Colm Gildernew, chair of Stormont's Health Committee, said any potential treatment must be available on a free and universal basis.
"I welcome the reports that progress is being made on the development of a vaccine. We have seen the devastation Covid-19 has caused," he said.
"In particular, we have evidence that the virus has affected more deprived communities, causing considerable additional hardship to those who already endure significant inequalities.
"If there is hope on the horizon, it must be hope for all.
"In the meantime, we must concentrate on fighting the pandemic with proactive public health measures and investment in finding the virus, testing, tracing, isolating and supporting our entire community."
While mass vaccinations might not be available until 2021, Dr Bamford is also hopeful that the vaccine could be ready before the end of the year.
"This is the good news day we've been waiting for and that needs to be celebrated," he said.
"It's a brand new kind of vaccine and the better news is that there are several more vaccines being worked on that follow the same technique.
"Results show we are seeing people protected against the virus and being prevented from getting very sick. It's all very promising.
"It's also working well with older people, which is a concern with any new vaccine.
"The only downside so far is the logistics of getting the vaccine out into the community.
"It has to be kept at -70 or -80 degrees, so that can be problematic, but aside from that, it all looks positive that by the end of the year we can see some people start receiving the vaccination."
No vaccine has gone from the drawing board to being proven highly effective in such a short period of time and the UK has already secured 40m doses of the Pfizer/BioNTech drug, the first agreement the firms signed with any government. It is thought people will need two doses three weeks apart, meaning not enough has yet been secured for the entire population.
GP magazine Pulse reported recently that family doctors will be told to be prepared to start vaccinating over-85s and front line workers from early next month. The UK's Joint Committee on Vaccination and Immunisation, an independent expert advisory group, will advise the Government on which groups get priority. Alliance health spokeswoman Paula Bradshaw MLA said challenges remain in bringing the potential vaccination to the public.
"The whole process, including distribution, will take many months even if all goes perfectly," she warned.
"For now we await the outcome of further safety tests and the detail of the protection offered. We now require a four-nation agreement on how to take logistics forwards and ensure the most vulnerable are protected."
SDLP health spokesman Colin McGrath MLA said the vaccine breakthrough was welcome but people should still stick to rules.
"I urge the Minister for Health to ensure that the vaccine is procured at our earliest opportunity so it can be rolled out across society, ensuring that everyone has access, but prioritising those most vulnerable groups," he said.
"However, while this is good news and provides a glimmer of hope, we must continue to follow the public health advice and act to save lives."
Pfizer and BioNTech are expected to submit an application for emergency use authorisation to the US Food and Drug Administration within the next fortnight.
The companies expect to be able to produce up to 50m vaccine doses globally in 2020 and up to 1.3bn in 2021.
