The biotech company Pfizer said Wednesday that a completed study of its experimental Covid-19 vaccine showed it is 95 percent effective.
Pfizer said the vaccine had no serious side effects and that the company will apply for emergency use authorisation from US regulators "within days."
The announcement came as coronavirus cases are surging in the US and other parts of the world, and boosted hopes for an end to the pandemic that has upended life around the globe.
"The study results mark an important step in this historic eight-month journey to bring forward a vaccine capable of helping to end this devastating pandemic," said Pfizer CEO Albert Bourla.
"With hundreds of thousands of people around the globe infected every day, we urgently need to get a safe and effective vaccine to the world," he added.
Pfizer had said last week after a preliminary analysis that its product was more than 90 percent effective.
On Monday another biotech firm involved in the race to develop a vaccine, Moderna, said its own vaccine was 94.5 percent effective, according to a preliminary analysis.