The UK is to give £500m to a new global vaccine-sharing scheme designed to ensure treatments for Covid-19 are distributed fairly.
Prime Minister Boris Johnson made the announcement in a speech to the United Nations general assembly.
He called on world leaders to overcome their differences as he set out plans to prevent future global pandemics.
He also promised extra funding for the World Health Organization.
Mr Johnson told his foreign counterparts at the UN that the "notion of the international community looks tattered" after the Covid-19 crisis.
He called for states to "reach across borders and repair these ugly rifts", as he announced a plan, developed with the Bill and Melinda Gates Foundation and The Wellcome Trust, to help stop future pandemics.
The proposals include developing a global network of "zoonotic hubs" to identify dangerous pathogens before they jump from animals to humans, as well as improving manufacturing capacity for treatments and vaccines.
In a pre-recorded speech on Saturday afternoon, the prime minister said: "After nine months of fighting Covid, the very notion of the international community looks tattered.
"We know that we cannot continue in this way. Unless we unite and turn our fire against our common foe, we know that everyone will lose.
"Now is the time, therefore, here at what I devoutly hope will be the first and last ever Zoom UNGA, for humanity to reach across borders and repair these ugly rifts.
"Here in the UK, the birthplace of Edward Jenner who pioneered the world's first vaccine, we are determined to do everything in our power to work with our friends across the UN to heal those divisions and to heal the world."
Other measures being proposed include designing a global pandemic early warning system, improving the ability to collect and analyse samples and distribute the findings.
The plan also calls for common protocols to be agreed on sharing data.
Mr Johnson is also proposing states reduce trade barriers on Covid-critical products, such as soap, to help the global response.
The £500m in aid funding will go to the Covax vaccines procurement pool, which aims to help poorer countries access a coronavirus jab when one is developed.
There are about 40 different coronavirus vaccines in clinical trials - including one being developed by the University of Oxford that is in an advanced stage of testing.
A successful vaccine that can protect people from Covid-19 is still widely seen as the main exit strategy from the current restrictions on people's lives.
However, Mr Johnson said "we must never cut corners" or "sacrifice safety to speed" in the search for a vaccine.
"Because it would be an absolute tragedy if, in our eagerness, we were to boost the nut-jobs - the anti-vaxers, dangerous obsessives who campaign against the whole concept of vaccination and who would risk further millions of lives," he said.
The PM also promised £340m to the World Health Organization over the next four years - a 30% increase on the previous period, making the UK one of its biggest donors.
Romilly Greenhill, UK director of The One Campaign, which fights extreme poverty and preventable disease, said the British government was showing "powerful leadership" at a moment when it "could not be more important".
"It will give the global fight against Covid-19 a shot in the arm, helping ensure everyone, everywhere can access a vaccine."