The US has thrown its support behind a move at the World Trade Organization (WTO) to temporarily lift patent protection for coronavirus vaccines.
India and South Africa proposed the plan, which they said would increase vaccine production around the world.
But drugs manufacturers argue it may not have the desired effect.
US Trade Representative Katherine Tai said that "extraordinary times call for extraordinary measures".
And she warned that it would take time to reach an agreement on the matter.
One hundred members of the World Trade Organisation (WHO) are said to be in favour, and a panel on intellectual property is expected to discuss the issue next month.
Intellectual property means creations, such as inventions, which are protected by patents, copyrights, and trademarks - allowing the originator to be financially rewarded.
India and South Africa were the leading voices in a group of about 60 countries which for the last six months has been trying to get the patents on vaccines set aside.
However, they met with strong opposition from the previous US administration of Donald Trump, the UK, and the EU.
But Trump's successor as US President, Joe Biden, has taken a different tack. He backed a waiver on intellectual property associated with Covid vaccines during the 2020 presidential campaign and repeated his support on Wednesday.
The head of the WHO called the move a "monumental moment" in the fight against Covid-19.
