Pharmaceutical giant Pfizer and its German partner German partner BioNTech SE 22UAy.F have announced their experimental COVID-19 vaccine is more than 90 percent effective based on initial trial results.

Scientists, public health officials and investors welcomed the first successful interim data from a large-scale clinical test that could help turn the tide of the pandemic if the full trial results pan out, Reuters reported.

However, mass roll-outs, which need regulatory approval, will not happen this year and several vaccines are seen as necessary to meet massive global needs.

But if the vaccine gets the go-ahead, the companies estimate it can roll out up to 50 million doses this year, enough to protect 25 million people, and then produce up to 1.3 billion doses in 2021.

“Today is a great day for science and humanity,” said Pfizer Chief Executive Albert Bourla, noting the data milestone comes with “infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen.”

Experts said they wanted to see the full trial data, but the preliminary results looked encouraging.

“This news made me smile from ear to ear. It is a relief to see such positive results on this vaccine and bodes well for COVID-19 vaccines in general,” said Peter Horby, professor of emerging infectious diseases at the University of Oxford.

There are still many questions, such as how effective the vaccine is by ethnicity or age and how long immunity may last.

“But the bottom line is, as a vaccine it’s more than 90% effective, which is extraordinary,” top U.S. infectious diseases expert Dr Anthony Fauci told CNN.