World leaders launched a pledging "marathon" on Monday - without the United States - to raise at least 7.5 billion euros ($8.2 billion) for research into a possible vaccine and treatments for the coronavirus.
Organisers included the European Union, non-EU states Britain and Norway, as well as Japan, Canada and Saudi Arabia. They aim to raise funds over several weeks or months, building on efforts by the World Bank, the Bill and Melinda Gates Foundation and wealthy individuals.
"I believe the fourth of May will mark a turning point in our fight against coronavirus because today the world is coming together," the head of the European Commission, Ursula von der Leyen, said at the start of the event.
A list of world leaders due to speak seen by Reuters did not include any US officials. EU diplomats said the United States was not taking part, although it is a major donor to the United Nations and UN bodies. The US embassy in Brussels was not immediately available for comment.
President Donald Trump said on April 15 that he would halt funding to the World Health Organization (WHO), whose director general is due to address the conference, over its handling of the pandemic.
As organisers, France's President Emmanuel Macron, German Chancellor Angela Merkel and Japan's Prime Minister Shinzo Abe are among those due to speak. Chinese Premier Li Keqiang will also speak and make a pledge, according to the protocol list.
Von der Leyen last month called the online pledging conference "a real marathon", saying a vaccine for the respiratory disease COVID-19 was needed "in every corner of the world ... at affordable prices".
The size of donations may not be known immediately, and it is unclear how much of the pledges will represent new funding, as financial commitments made earlier this year will also be included.
Saudi Arabia, the current chair of the Group of 20 industrialised countries, has promised $500 million. Norway, Turkey and Israel are also expected to pledge.
The 7.5 billion euro target is an initial figure. Von der Leyen has said more money will be needed over time.
The Global Preparedness Monitoring Board, a UN-backed body focusing on health crises, estimates that the world needs at least $3.0 billion at once to develop, manufacture and distribute a possible vaccine against COVID-19, the EU Commission said.
Another $2.25 billion is needed to develop antiviral treatments for COVID-19, $750 million for testing kits, and another $750 million to stockpile essential protective equipment, such as face masks.
The remaining $1.25 billion included in the initial funding goal will go to WHO to support the most vulnerable countries.
Britain will hold another online donor summit on June 4.
Andrea Ammon, director of the European Centre for Disease Prevention and Control, said that, although the initial wave of transmissions of the coronavirus had passed its peak in most countries in Europe, "this is not going to end any time soon".
She told EU lawmakers on Monday that Bulgaria's rate of recorded infections was still rising, and in another four countries - Poland, Romania, Sweden and Britain - there had been "no substantial changes" in infection rates in the last 14 days.