Global leaders joined the World Health Organization (WHO) on Friday to launch an initiative to accelerate work on drugs, tests and vaccines against Covid-19 and to share them around the world.
French President Emmanuel Macron and European Commission President Ursula von der Leyen were among leaders taking part in a videoconference to announce the plan, but the United States stayed away.
"The world needs these tools and needs them fast," WHO Director General Tedros Adhanom Ghebreyesus said as the virtual meeting got under way. "We are facing a common threat which we can only defeat with a common approach."
The WHO said late on Thursday it would announce a "landmark collaboration" on Friday to speed development of safe, effective drugs, tests and vaccines to prevent, diagnose and treat Covid-19, the lung disease caused by the novel coronavirus.
A spokesman for the US mission in Geneva told Reuters before the meeting that the United States would not be involved.
"There will be no US official participation," he said in an email reply to a query. "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."
US President Donald Trump has lambasted the WHO as being slow to react to the outbreak and being "China-centric", and announced a suspension of funding to the UN agency.
More than 2.7 million people worldwide have been infected with Covid-19 and nearly 190,000 have died since the virus emerged in the central Chinese city of Wuhan late last year, according to a Reuters tally.
More than 100 potential Covid-19 vaccines are being developed, including six already in clinical trials, said Dr. Seth Berkley, CEO of the GAVI vaccine alliance, a public-private partnership that leads immunisation campaigns in poor countries.
"We need to ensure that there are enough vaccines for everyone, we are going to need global leadership to identify and prioritise vaccine candidates," he told a separate Geneva news briefing, before taking part in the formal WHO announcement.
Global manufacturing capacity must be ramped up ahead of choosing "a winner" vaccine, Berkley said, noting that GAVI and the World Bank were both looking at the issue.
"We can't have a repeat of what happened in 2009 - the H1N1 vaccine, when there was not enough supply for developing countries or when supply did come it came much later."
Another important question was how well a vaccine would work in people most at risk from Covid-19, Berkley said.
"How well do they work in the elderly, are they single or multiple dose etc?" he said, noting that older people had weaker immune systems.