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”.
Ms. Tai said the US would now embark on negotiations at the World Trade Organisation (WTO) to try to secure the waiver, but warned this could take time.
One hundred of the WTO’s 164 states are said to be in favour, and a panel on intellectual property is expected to discuss the issue next month.
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 Mr 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.
Reacting to the latest US move, the European Commission President Ursula von der Leyen said “the EU is also ready to discuss any proposals that address the crisis in an effective and pragmatic manner”.
The head of the World Health Organization called the US announcement a “monumental moment” in the fight against Covid-19.
Intellectual property describes creations, such as inventions, which are protected by patents, copyrights and trademarks. These prevent copying and allow the originator to be financially rewarded.
Patents give innovating firms a short-term monopoly on production to cover the costs of development and encourage investment.
Biotech firms argue that such protection has provided incentives to produce Covid vaccines in record times.
If approved, supporters say, the waiver would allow production of vaccines to be ramped up and provide more affordable doses for less wealthy countries.
Many developing countries have argued that rules requiring countries to protect patents and other forms of intellectual property are an obstacle to increasing the production of vaccines and other products needed to tackle the pandemic.
Tedros Adhanom Ghebreyesus, head of the WHO, called the US decision “historic” and said it marked “a monumental moment in the fight against Covid-19”.