(Reuters) – Pfizer Inc on Monday said its experimental vaccine was more than 90% effective in preventing COVID-19 based on initial data from a large study, a major victory in the fight against a pandemic that has killed over 1 million people, roiled the world’s economy and upended daily life.

Pfizer and German partner BioNTech SE are the first drugmakers to show successful data from a large-scale clinical trial of a coronavirus vaccine. The companies said they have so far found no serious safety concerns and expect to seek U.S. emergency use authorization later this month.

If authorized, the number of vaccine doses will initially be limited. Many questions also remain including how long the vaccine will provide protection. However the news provides hope that other vaccines in development against the novel coronavirus may also prove effective.

“Today is a great day for science and humanity,” Albert Bourla, Pfizer’s chairman and chief executive, said in a statement. “We are reaching this critical milestone in our vaccine development program at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen.”

Pfizer expects to seek broad U.S. emergency use authorization of the vaccine for people aged 16 to 85. To do so, it will need to have collected two months of safety data on around half of the study’s roughly 44,000 participants, expected in late November.

“I’m near ecstatic,” Bill Gruber, one of Pfizer’s top vaccine scientists, said in an interview. “This is a great day for public health and for the potential to get us all out of the circumstances we’re now in.”