GENEVA/ZURICH • The global death toll from Covid-19 could double to two million before a successful vaccine is widely used and could be higher without concerted action to curb the pandemic, a World Health Organisation (WHO) official said.

"One million is a terrible number and we need to reflect on that before we start considering a second million," the WHO's emergencies director Michael Ryan told reporters on Friday when asked how high the death toll could go. "Are we prepared collectively to do what it takes to avoid that number?

"Unless we do it all, (two million deaths)... is not only imaginable but sadly very likely," he said.

Dr Ryan's comments came as world leaders at the United Nations General Assembly called for global unity to fight the pandemic, which has killed just under one million people and infected nearly 33 million globally.

British Prime Minister Boris Johnson was due yesterday to pledge £340 million (S$597 million) in funding for the WHO spread across four years - a 30 per cent increase on the previous four-year commitment - with around a third of the money dependent on reform in the organisation.

He will call for a revival of cross-border cooperation and was due to present a five-point plan to improve the international response to future pandemics.

"After nine months of fighting Covid, the very notion of the international community looks tattered," says Mr Johnson, according to advance extracts distributed by his office. "Unless we unite and turn our fire against our common foe, we know that everyone will lose. Now is the time therefore... for humanity to reach across borders and repair these ugly rifts."

His plan includes a global network of research hubs and more vaccine manufacturing capacity.

He will commit an initial £71 million to the global vaccine partnership known as Covax to secure purchase rights on 27 million doses, and £500 million to a separate Covax initiative to help poorer countries access a vaccine.

Indian Prime Minister Narendra Modi pledged yesterday that his country's vaccine production capacity would be made available globally to fight the pandemic.

"India's vaccine production and delivery capacity will be used to help all humanity in fighting this crisis," he said in his recorded address to the UN assembly.

Australian Prime Minister Scott Morrison on Friday insisted that any nation that develops a Covid-19 vaccine share it universally, warning that history will be a "severe judge" if not. His strongly worded appeal comes as the US, a historic ally of Australia, resists global efforts to collaborate on a vaccine. "When it comes to a vaccine, Australia's view is very clear - whoever finds the vaccine must share it," he said in his video message.

Latin American leaders also appealed to the UN for free access to a future vaccine, urging major powers to share their know-how for the sake of global well-being.

Latin America has taken a heavy blow from Covid-19 with nearly nine million cases and more than 330,000 deaths, one third of the global total, according to an Agence France-Presse tally based on official data. "With the pandemic, as with poverty, nobody will be saved on their own," Argentine President Alberto Fernandez said.

The Covax Facility is coordinated by the WHO and funded by it, with additional funding provided by the United Nations children's fund (Unicef), the Bill and Melinda Gates Foundation as well as the World Bank. More than 150 nations have joined the initiative, which aims to have two billion doses of a vaccine ready for universal distribution by late next year.

Globally, the pandemic shows no signs of slowing. More than 200,000 people have died in the US, which has just over seven million cases, the highest of any nation. On average, the country is reporting 44,000 new cases a day and about 700 deaths, with a surge in mid-western states worrying health officials.

India has emerged as a global coronavirus hot spot that could potentially outstrip the US at the rate its daily cases are rising. In the last 24 hours up to yesterday, the country added 85,362 new infections, taking the total past 5.9 million cases.

REUTERS, AGENCE FRANCE-PRESSE