BRUSSELS -- The European Union's executive said Tuesday it will sign a contract for up to 160 million doses of the experimental coronavirus vaccine developed by Moderna.

Ursula von der Leyen, the president of the EU Commission, said the deal will be approved on Wednesday as the EU tries to build "one of the most comprehensive COVID-19 vaccine portfolio in the world."

The deal with Moderna is the sixth secured by the EU Commission with pharmaceutical companies, allowing its 27 member countries to buy more than one billion doses once the shots are ready.

"We are working on yet another one," von der Leyen said Tuesday.

Earlier this month, Moderna said its vaccine appears to be 94.5% effective, according to preliminary data from the company's study.

The commission said that once a vaccine is ready, all EU countries will receive it at the same time on a pro rata basis.

Meanwhile, a group of airlines and airport operators said they will join in December an initiative to adopt the use of a digital health pass for passengers that can demonstrate travellers' COVID-19 status.

The hard-hit aviation industry has been pushing for the implementation of such apps in addition to rapid tests for air passengers to reduce the need for post-arrival quarantines and to give airlines a boost. The European Commission has also been encouraging its 27 members to use a common set of COVID-19 tests to facilitate cross-border travel during the pandemic.

Backed by The Commons Project Foundation and the World Economic Forum, "CommonPass" uses a standardized digital certificate that needs to be downloaded on a phone.

"CommonTrust Network airlines JetBlue, Lufthansa, Swiss International Airlines, United Airlines, and Virgin Atlantic will begin the roll-out of CommonPass in December on select flights departing from New York, Boston, London, and Hong Kong," the groups said in a statement.