On the eve of the summit, Biden, who is making his first foreign trip as president, announced that the US will purchase 500 million doses from Pfizer and will supply half of all the vaccines set to be shared globally.
Underpinning the US-led diplomatic revival, Biden and British Prime Minister Boris Johnson on Thursday adopted a new "Atlantic Charter", modeled on the pact signed by their World War II predecessors to help build a new world order.
Campaigners say the G7's vaccine donations pledge for this year and next - including 500 million U.S. doses - is far too little, too late to end a pandemic that has claimed over 3.7 million lives worldwide.
They will also debate aiding poorer nations to transition out of fossil fuels, in the build-up to the UN's COP26 climate summit in November in Scotland.
Four dead, one in hospital after pedestrians hit by vehicle
Ontario Premier Doug Ford says justice must be served "for the horrific act of hatred" that occurred in London, Ont., on Sunday. He said London police were working with federal police and prosecutors to see about potential terrorism charges.
Police have closed off roads and coastal paths to Carbis Bay, the small seaside resort which is hosting the event, erecting steel fences and putting other restrictions in place.
The steps to prevent future pandemics include slashing the time taken to develop and license vaccines, treatments and diagnostics for any future disease to under 100 days.
Dr Tedros stressed that "the world needs a stronger global surveillance system to detect new epidemic and pandemic risks".
However, Oxfam said the declaration "does nothing to address the fundamental problems that are preventing vaccines being accessible to the vast majority of humanity".
The declaration is expected to be signed by all of the G7 leaders on Saturday afternoon following a session discussing the response to the pandemic.