The European Union has acquired 1.96 billion doses of COVID-19 vaccines for its 446 million people after striking a deal with America's Moderna, Inc.

The EU agreed to buy up to 160 million doses of Moderna's COVID-19 vaccine candidate, European Commission president Ursula von der Leyen said.

"I am happy to announce that we will approve a new contract to secure another COVID-19 vaccine," she said. Last week, Moderna said its experimental synthetic messenger RNA, two-dose vaccine was 94.5% effective in preventing COVID-19 based on interim data from a late-stage clinical trial.

Sources said the EU intended to pay below $25 a dose. Moderna chief executive Stephane Bancel said the company would charge between $25 and $37 a dose - depending on the amount ordered.

Actual purchases will be made by individual union governments if the vaccine is approved by the European Medicines Agency.

In August the commission said it had held preliminary talks with Moderna over a deal for 80 million doses and an option for 80 million more.

The deal with Moderna announced is the sixth supply deal the union has negotiated. It has already struck deals with AstraZeneca, Pfizer-BioNTech, Sanofi-GSK, Johnson & Johnson and CureVac. It is also in talks to buy the COVID-19 vaccine being developed by Novavax, Inc.

The union said it will earmark some doses for COVAX, an international project to deliver safe and effective vaccines to the world's poorest people.

The union joined COVAX, which is led by the World Health Organization, in September. The commission will provide up to $475 million in guarantees for COVAX and its objectives.

Europe is providing experts and cash for COVAX to accelerate the development and manufacturing of an international supply of vaccines for citizens in all countries.

COVAX discourages governments from hoarding vaccines and asks them to concentrate on vaccinating the most at-risk people first.