UPDATE 1-Four EU states urge EU to safeguard Johnson & Johnson vaccine supply

Adds background, details

ATHENS, Feb 5 (Reuters) - The leaders of Denmark, Austria, the Czech Republic and Greece have urged the European Commission to act quickly to secure supplies of the COVID-19 vaccine developed by U.S. drugmaker Johnson & Johnson.

In a letter addressed to Commission President Ursula von der Leyen they said they had been informed that the new vaccine needed to be shipped to the United States for filling and finishing.

"If this could risk EU access to the vaccines, we should consider addressing the issue already now with a view to finding solutions with the company in order to safeguard European supply," they said.

They said they understood capacity was available in Europe to perform filling and finishing, a late stage in the manufacturing process that covers formulating the licensed active substance and filling it into vials.

The letter comes as the Commission has faced criticism for its handling of the vaccines issue and for a damaging row with Anglo-Swedish pharmaceuticals group AstraZeneca. European Union countries have so far lagged far behind others such as Israel, Britain and the United States in rolling out vaccines.

Describing Johnson & Johnson's single-dose shot as a "potential game changer", they said it was important to engage with vaccine producers "to mitigate potential problems before they arise".

"In view of the importance attached to these issues, we would encourage an early dialogue at the highest levels."

They also called for speedy contract negotiations with all promising new candidates, such as those from Novavax Inc or Valneva, and said "approval of all new vaccines will need to be as swift as possible while respecting necessary health requirements".

The letter was signed by Austrian Chancellor Sebastian Kurz, Czech Prime Minister Andrej Babis, Danish Prime Minister Mette Frederiksen and Greek Prime Minister Kyriakos Mitsotakis.

(Writing by James Mackenzie; Editing by John Stonestreet and Alex Richardson)

((james.mackenzie@thomsonreuters.com; +39 02 66129533 ; Reuters Messaging: Reuters Messaging james.mackenzie.reuters.com@reuters.net))