European Commission President Ursula von der Leyen. (Photo:REUTERS/Yves Herman/Pool)

US President Joe Biden voiced support on Wednesday for a waiver in a reversal of the US position, and his top trade negotiator, Katherine Tai, swiftly endorsed negotiations at the World Trade Organization.

The WHO and the WTO welcomed the US move.

Von der Leyen, speaking to the European University Institute in Florence, said the EU was ready to discuss any proposals that address the crisis "in an effective and pragmatic manner".

But drugmakers said the proposal could have the opposite effect, by disrupting a stretched and fragile supply chain. They urged rich countries instead to share vaccines more generously with the developing world.

Germany also rejected the idea, saying the reasons for the lack of vaccines were capacity and quality standards. A government spokeswoman said in a statement that "the protection of intellectual property is a source of innovation and must remain so in the future".

The International Federation of Pharmaceutical Manufacturers and Associations said a waiver would encourage new manufacturers who lacked essential know-how and oversight.