Democratic presidential nominee Joe Biden spoke Friday in Grand Rapids about his plans for the economy, capping off a chaotic 24 hours of uncertainty.

Details of the visit were first announced Thursday, but were thrown into question after President Donald Trump announced late Thursday night that he had tested positive for COVID-19.

Trump and Biden had both attended the first presidential debate earlier in the week in Cleveland, meaning Biden had possibly been exposed to the virus.

Biden was tested Friday morning, before any decisions were made about whether to proceed with the Grand Rapids speech, and the test came back negative.

But Biden could still test positive at a later date; the virus has an estimated mean incubation period of five to seven days, and it has only been three days since the debate.

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“I’d like to start by acknowledging – which I’m sure all of you do as well – sending my prayers for the health and safety of the first lady and president of the United States after they tested positive for COVID-19,” Biden said.

“This is not a matter of politics. It’s a bracing reminder for all of us that we have to take this virus seriously. It’s not going away automatically. We have to do our part to be responsible,” Biden continued. “We can save 100,000 lives in the next 100 days according to the head of the CDC if everyone wears a mask in public. So be patriotic. It’s not about being a tough guy; it’s about doing your part.”

A second speech planned for Grand Rapids, a voter mobilization event, was canceled Friday afternoon.

“We were supposed to have an event after this, at a headquarters, but based on the crowd size and indoors, it was concluded by the docs that it was best not to do it,” Biden said.

The Friday remarks were Biden’s first public appearance since the news broke overnight that Trump and first lady Melania Trump had tested positive for the virus.

Biden said the cases demonstrate the need for a nationwide testing and contact tracing plan.

“We need regular testing, with results turned around rapidly, and that’s available to everyone,” Biden said. “It’s not just the folks in the White House or who travel with me that deserve regular testing; it’s folks in the meat packing and food processing plants, grocery store workers – every single American deserves safety and peace of mind.”

Biden hinted that Trump testing positive is a result of his failure to contain the virus and refusal to listen to the advice of medical experts when it comes to things like mask wearing and not holding mass gatherings.

“We need to take the science of fighting this disease seriously if we are going to save lives,” Biden said. “Above all, the news is a reminder that we, as a nation, need to do better in dealing with this deadly pandemic.”

Biden wished the president and first lady a speedy recovery at multiple points in the speech.

“I hope that all those who are fighting this virus – including the first family and so many other Americans today – recover soon,” Biden said.