Democratic presidential hopeful Joe Biden and his running mate Kamala Harris put the coronavirus pandemic front and center in their campaign Thursday, targeting Donald Trump's response to the health and economic crises ahead of November's election.

Fresh off Wednesday's campaign rollout that featured the pair together for the first time showcasing their vision for the nation, they met with public health experts in Delaware.

They were then to hold a session on the pandemic's impact on businesses and employment in the world's largest economy.

"As the (former) vice president has been saying since the beginning of this pandemic, it should be the public health professionals that are leading policy in our country to address this lethal pandemic," Harris told reporters as she and Biden held a virtual meeting with five health experts.

The panel included former surgeon general Vivek Murthy, who has been an advisor to Biden throughout the coronavirus crisis.

Democrats widely accuse Trump of mishandling the US response to a pandemic that has claimed more than 166,000 lives, the world's highest death toll.

Critics have blamed him for voicing falsehoods about the virus, including that children are "almost immune" to COVID-19, and ignoring or sidelining some chief scientists and health officials in his administration.

By staging the day's events at the start of their campaign, Biden and Harris are signaling to voters that the virus crisis is a top priority -- and a major election issue.

On Monday, the Democratic National Convention begins -- online -- to formally nominate Biden and his running mate.

The party's presidential hopeful introduced Harris at a rollout event Wednesday near his home in Wilmington, at a gymnasium with no public access due to coronavirus concerns.

Harris was announced as Biden's VP pick a day earlier, sparking a grassroots fundraising spree that the campaign said raised an eye-popping $34.2 million by the end of Wednesday.

Democratic presidential nominee Joe Biden and his running mate Kamala Harris have launched their campaign to oust President Donald Trump from the White House in the November 3, 2020 election
Democratic presidential nominee Joe Biden and his running mate Kamala Harris have launched their campaign to oust President Donald Trump from the White House in the November 3, 2020 election AFP / Olivier DOULIERY

At the rollout, Harris said Trump's "mismanagement" of the pandemic has plunged the nation into its deepest health crisis in a century and the worst economic downturn since the Great Depression.

"There's a reason (the coronavirus) has hit America worse than any other advanced nation. It's because of Trump's failure to take it seriously from the start," she said.

Harris lamented "his refusal to get testing up and running. His flip-flopping on social distancing and wearing masks. His delusional belief that he knows better than the experts."

Trump meanwhile said the economy was experiencing a "v-shaped recovery," despite millions of American families suffering and analysts warning that the country remains in an unemployment crisis.

"As we continue to confront the China virus, we're rebuilding America's economy like nobody thought possible, actually," Trump said Wednesday at the White House.

"We're doing incredibly well."

The Republican incumbent took a swing early Thursday at his White House challengers, calling Harris, a US senator from California, part of the "radical left" and saying a Biden presidency would trigger economic disaster.

As for the coronavirus, "it will be going away," Trump told Fox Business Network.

"They scream, 'How can you say that?'" Trump added. "I said, because it's going to be going away."