The UK is now the biggest contributor to the international fund to find a Covid-19 vaccine – pledging a total of £544 million.
New funding was also announced by the UK to accelerate production of rapid tests and treatments for the virus, for use in Britain and around the world.
Boris Johnson called on governments around the world to work together to create a vaccine as quickly as possible and make it available to anyone who needs it.
"While our brilliant doctors and nurses fight coronavirus at home, this record British funding will help to find a vaccine for the entire world,” Mr Johnson said.
“UK medics and researchers are at the forefront of this pioneering work.
“My call to every G20 country and to governments around the world is to step up and help us defeat this virus.”
The video call between G20 leaders was the first virtual meeting of the group since the coronavirus outbreak.
The G20 leaders also discussed the international effort to protect the global economy from the long-term effects of the virus.
An intensive care doctor working in Cambridge explains how a mechanical ventilator works
A statement from the G20 leaders’ summit said the Covid-19 pandemic is a “powerful reminder of our interconnectedness and vulnerabilities”.
“The virus respects no borders,” the statement said.
“Combatting this pandemic calls for a transparent, robust, coordinated, large-scale and science-based global response in the spirit of solidarity. We are strongly committed to presenting a united front against this common threat.”
The funding will be channelled to the Coalition for Epidemic Preparedness Innovations (CEPI) – it is supporting the development of vaccines that will be available throughout the world.
CEPI has announced it requires an additional $2 billion (£1.6 billion) of funding from international Governments to develop the crucial vaccine.
The UK had previously pledged £71 million for the research of vaccines and diagnostic tests, to support the World Health Organisation (WHO) and other international humanitarian organisations.
Chancellor Rishi Sunak also announced up to £150 million in the Budget for the International Monetary Fund to help mitigate the impact of coronavirus on the world’s most vulnerable countries.
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