Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX) moved one step closer to potentially selling doses of their coronavirus vaccine, BNT162b2, to EU member states. Investors have known since mid-July that the duo was in talks with the European Commission. But, as governments are apt to do, it's taken awhile to get the deal done.

The sides have completed "exploratory talks" and will now enter "contract negotiations." They are at the point where they've decided how many doses the contract will cover -- 200 million with an option for another 100 million doses -- but haven't determined the cost the EU member states will pay. If they can reach an agreement, Pfizer and BioNTech would begin supplying the vaccine by the end of 2020, subject to an approval by EU regulators.

Doctor giving a shot to a child holding a stuffed animal.

Image source: Getty Images.

The drugmakers announced a deal with the U.S. government in July to sell 100 million doses of BNT162b2 for $19.50 per dose. The government has an option to purchase an additional 500 million doses.

Worldwide, Pfizer and BioNTech expect to have 100 million doses ready by the end of 2020 and approximately 1.3 billion doses available by the end of 2021. The vaccine requires an initial dose and a booster shot, so the actual number of people who can be treated is half of the number of available doses.

BNT162b2 is currently being tested in a phase 2/3 clinical trial, which, as of Monday, had enrolled 25,189 of the expected 30,000 participants. Initial data from the study may be available as early as October, although the exact timing will be based on how quickly people in the clinical trial develop COVID-19, the disease that's caused by the novel coronavirus.