Pfizer Inc’s PFE.N experimental COVID-19 vaccine is more than 90% effective based on initial trial results, the drugmaker said on Monday, a major victory in the war against a virus that has killed over a million people and battered the world’s economy.

Pfizer experimental COVID-19 vaccine

Scientists, public health officials and investors welcomed the first successful interim data from a large-scale clinical test as a watershed moment that could help turn the tide of the pandemic if the full trial results pan out. However, mass roll-outs, which needs regulatory approval, will not happen this year and several vaccines are seen as necessary to meet massive global needs.

Pfizer and German partner BioNTech SE 22UAy.F said they had found no serious safety concerns yet and expected to seek U.S. emergency use authorization this month, raising the chance of a regulatory decision as soon as December.

If granted, the companies estimate they 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.

Pfizer expects to seek U.S. emergency use authorization for people aged 16 to 85. To do so, it will need two months of follow-up safety data to assure no side effects crop up. That is expected to be available in the third week of November.

U.S. Health and Human Services Secretary Alex Azar said it would take several weeks for U.S. regulators to receive and process the data before a potential approval.