Biden voiced his support for a temporary waiver - a sharp reversal of the previous US position - after a speech at the White House, followed swiftly by a statement from his chief trade negotiator, Katherine Tai.

"This is a global health crisis, and the extraordinary circumstances of the COVID-19 pandemic call for extraordinary measures," Tai said on Wednesday.

Shares in a number of makers of vaccines for COVID-19 tumbled on the news. Two of the biggest vaccine makers are US companies - Moderna and Pfizer.

Biden's move won praise from the head of the World Health Organisation, Tedros Adhanom Ghebreyesus, who called it a "MONUMENTAL MOMENT IN THE FIGHT AGAINST #COVID19" on Twitter.

But the pharmaceutical industry's biggest lobby group warned that Biden's unprecedented step would undermine the companies' response to the pandemic and compromise safety.

Biden, who backed a waiver during the 2020 presidential campaign, has made fighting the coronavirus a top priority of his administration and the rollout of vaccines in the United States has led to a decline in case numbers and deaths.

The Democratic president, who campaigned on a promise to re-engage with the world after four years of contentious relations between former president Donald Trump and US allies, has come under intensifying pressure to share US vaccine supply and technology to fight the virus around the globe.

His decision comes amid a devastating outbreak in India, which accounted for 46 per cent of the new COVID-19 cases recorded worldwide last week, and signs the outbreak is spreading to Nepal, Sri Lanka and other neighbours.

Wednesday's statement paved the way for what could be months of negotiations to hammer out a specific waiver plan. WTO decisions require a consensus of all 164 members.

Tai said the United States would take part in text-based negotiations at the WTO to ensure the waiver could happen, but cautioned those deliberations would take time.

The United States and several other countries previously blocked negotiations at the WTO about a waiver proposal led by India and South Africa and aimed at helping developing countries produce COVID-19 vaccines using the IP of pharmaceutical companies.

Tai said: "The administration believes strongly in intellectual property protections, but in service of ending this pandemic, supports the waiver of those protections for COVID-19 vaccines."

A person familiar with the US consultations on the issue said Wednesday's decision allowed Washington to be responsive to the demands of the left and developing countries, while using WTO negotiations to narrow the scope of the waiver.

Since the negotiations will take time, the decision also buys time to boost vaccine supplies through more conventional means.

Australian Associated Press