The European Union on Friday reached the first agreement to supply EU member countries with an experimental coronavirus vaccine, negotiating with AstraZeneca for the purchase of 300 million doses of the British drugmaker’s shot.The deal extends an earlier deal arranged by four EU countries — France, Germany, Italy and the Netherlands — to buy a similar number of doses from AstraZeneca, which licensed its vaccine from the University of OxfordThe European Commission, which is leading vaccine procurement discussions for 27 EU countries, also said Thursday it had concluded “exploratory talks” with Johnson & Johnson for access to the pharmaceutical giant’s vaccine candidate. Negotiations with partners Sanofi and GlaxoSmithKline have advanced to a similar stage as well.

Compared to the U.S. and the U.K., the European Union hasn’t moved as quickly to strike bilateral deals with vaccine developers. The agreement with AstraZeneca is its first, while the U.S. has already agreed to buy some 800 million doses from six drugmakers, and the U.K. 280 million from five.

In addition to the 300 million doses secured, the European Commission also negotiated an option to purchase 100 million more — a structure similar to some of the contracts signed by the U.S. Financial terms weren’t disclosed.

The AstraZeneca agreement emerged after weeks of “intense” negotiations, said EC President Ursula von der Lyen in a statement. Should the ongoing discussions with J&J and the team of Sanofi and GSK bear fruit, the EU could gain access to another 500 million doses.

All of these deals are being hammered out before the studies needed to prove any vaccine is actually protective are completed. Candidates from Moderna, AstraZeneca and partners Pfizer and BioNTech are the furthest along, having advanced into large, late-stage tests.

While the extensive dealmaking hedges against the risk of any one candidate failing, the rush by developed nations to secure a spot in line for first supply raises the risk doses will not be available for lower- or middle-income countries.

In announcing the AstraZeneca deal, the EC said the doses it plans to buy could be donated to those nations, or re-directed to other European countries outside of the bloc.

The World Health Organization, however, is already trying to do something similar, having announced in June the creation of a vaccine buying pool that’s designed to ensure access for high-risk groups around the world. The plan, which is being carried out with the help of two vaccine groups, hinges on funding commitments from wealthier nations to preorder supplies that would then be allocated equitably.

AstraZeneca, meanwhile, has enlisted the help of vaccine manufacturers around the world that it says brings annual production capacity to some 3 billion doses. The drugmaker has also been one of the most active in reaching agreements to dole out that supply, contracting with the U.S., U.K., Brazil, Argentina, Mexico and two vaccine groups.