The race for a vaccine to combat the new coronavirus is moving faster than researchers and drugmakers expected, with Pfizer Inc. joining several other groups saying that they had accelerated the timetable for testing and that a vaccine could be ready for emergency use in the fall.

Pfizer said Tuesday it will begin testing of its experimental vaccine in the U.S. as early as next week. On Monday, Oxford University researchers said their vaccine candidate could be available for emergency use as early as September if it passes muster in studies, while biotech Moderna Inc. said it was preparing to enter its vaccine into the second phase of human testing.

Johnson & Johnson said earlier this month it shaved months off the usual timelines for developing a vaccine, and expects to start human testing of a coronavirus candidate as soon as September, with possible availability on an emergency-use basis in early 2021.

“This is a crisis right now, and a solution is desperately needed by all,” said Pfizer Chief Executive Albert Bourla.

The experimental vaccines still face a gauntlet of testing to make sure they work safely, which could derail efforts. Many promising drugs and vaccines wind up faltering during rounds of study. The average vaccine takes about 10.7 years to develop from its preclinical phase and has a market entry probability of 6%, according to a 2013 study published by PLOS ONE.