Pharmaceutical giant Pfizer says that its experimental coronavirus vaccine is more than 90% effective.
That's based on initial data from a large study.
It would mark 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 its German partner BioNTech are the first drugmakers to show successful data from a large-scale clinical trial of a coronavirus vaccine.
The companies says they have so far found no serious safety concerns and expect to seek authorization for emergency use in the United States 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.
Pfizer said the interim analysis was conducted after 94 participants in the trial developed COVID-19, examining how many of them received the vaccine versus a placebo.
The data have yet to be peer-reviewed or published in a medical journal.
Pfizer said it would do so once it has results from the entire trial.
Pfizer and BioNTech have a $1.95 billion contract with the U.S. government to deliver 100 million vaccine doses beginning this year.
They've also reached supply agreements with the European Union, the UK, Canada and Japan.