US pharmaceutical giant Pfizer and German firm BioNTech applied to the US Food and Drug Administration (FDA) on Friday for the emergency use of their Covid-19 vaccine.
"It is with great pride and joy, and even a little relief, that I can say that our request for emergency use authorization for our Covid-19 vaccine is now in the FDA's hands," Pfizer chief executive Albert Bourla said in a video included in a tweet announcing the submission.
He called it "a historic day for science and for all of us."
In an earlier joint statement, the companies said they are ready to start distributing the drug "within hours after authorization" and that the regulator's approval could "enable the use of the vaccine in high-risk populations in the US by the middle to end of December 2020."
The vaccine, which is based on mRNA technology which draws on the genetic code of the coronavirus to train the body's immune system, has been found to be 95-per-cent effective in clinical trials.
The developers say no serious safety concerns have been observed.
Pfizer and BioNTech are the first Western producers of an experimental vaccine to produce promising results and apply for FDA authorisation.
Approval in Europe is pending and a process known as a rolling review is underway with regulators in the European Union as well as Britain.
European Commission President Ursula von der Leyen said on Thursday that approval from the European Medicines Agency (EMA) could come in the second half of December.
It is unclear how long the FDA's process will take, although US experts have expressed confidence that a decision will be made by the end of the year.
The companies expect to supply up to 50 million vaccine doses globally in 2020, increasing to up to 1.3 billion doses in 2021.
US officials have said there could be enough doses to inoculate some 20 million Americans by the end of the year.
"Our work to deliver a safe and effective vaccine has never been more urgent, as we continue to see an alarming rise in the number of cases of Covid-19 globally," Bourla said.
One advantage of mRNA vaccines is that they can be produced significantly more quickly than conventional vaccines.
However, the Pfizer/BioNTech vaccine must be stored at minus 70 degrees Celsius, leading to doubts about its logistical practicality.
Pfizer says it "has vast experience and expertise in cold-chain shipping and has an established infrastructure to supply the vaccine worldwide."
Pfizer and its much smaller German partner, based in the western city of Mainz, are competing against a number of other pharmaceutical companies also in the advanced stages of developing a vaccine, including Johnson&Johnson, AstraZeneca and Sanofi-GSK.
In Russia, China and most recently Bahrain, vaccines have already been made available and some of the population has received the jab.
However, it remains unclear how effective these vaccines are and what side effects they could have.