A spokesman for the US mission told Reuters that "there will be no US official participation" in the programme, which aims to speed the development of a vaccine and share resources in the fight against the virus.
He said: "We look forward to learning more about this initiative in support of international cooperation to develop a vaccine for Covid-19 as soon as possible."
The nation's withdrawal from collaborative international efforts in the wake of the pandemic follows Donald Trump's announcement that the US would suspend funding to the WHO after he accused the United Nations agency of "covering up" the coronavirus outbreak from China. He attacked the organisation as he faced similar criticisms after reports showed that he had dismissed or ignored warnings about the threat of the outbreak from his administration for several weeks.
President Macron told the meeting that the group hopes to "reconcile around this joint initiative both China and the US, because this is about saying the fight against Covid-19 is a common human good and there should be no division in order to win this battle."
The group has pledged to provide access to treatment and vaccines to other nations, commit to the international partnership and share research efforts and make informed group decisions about their response.
Its pledges starkly contrast with the largely isolationist tone of the Trump administration's response, leaving state and local governments to fend for themselves absent a consistent federal effort that could rely on a global support network.
The US is suspending $400m in funds for WHO after the president claimed that the organisation took China's claims about the virus "at face value" and now must be "held accountable".
WHO general-director Tedros Adhanom Ghebreyesys said last week that "now is the time for us to be united against a common struggle" in his rebuke of the president's claims.
He said: "When we're divided, the virus exploits the cracks between us."
The director-general had previously criticised the president for politicising the virus, saying that "now is not the time for pointing fingers".
Based on WHO's 2020-2021 budgets, the president's funding suspension could jeopardise millions of dollars in funding for polio, tuberculosis and HIV/AIDS treatment, as well as programmes for vaccine-preventable diseases and controlling disease outbreaks.
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