With vaccines on the move there is light at the end of the tunnel -- but Slaoui warned the situation will "get worse" before it gets better.
The visit followed the hospital's mask protocols for public speakers, based on the District of Columbia health guidance.
Although the door has all but shut on his efforts to overturn the vote results, Trump has remained defiant.
Ahead of Biden's inauguration one major formality remains, when Congress, presided over by Vice President Mike Pence, opens up and counts the electoral votes on January 6.
The lawsuit came as all 50 states plus Washington, DC have formally certified their vote tallies, opening the way to convene the Electoral College in five days.
Obama's claim comes amid reports that outgoing President Donald Trump's son, Donald Trump Jr., is preparing for a political career.
According to Melania's statement, it is meant to be used solely by first families for "leisure time."
For the third day in a row, the United States on Saturday notched a record number of coronavirus cases in 24 hours, reaching nearly 230,000 new infections.
Trump has barely left the White House since Biden was projected winner of the election on November 7, though he has made a number of trips to his nearby golf course.
The staff at Mar-a-Lago in Florida have been making preparations for the arrival of the Trump family.
The probe, led by the D.C. attorney general, is looking into the spending of the Trump inaugural committee.
As of Monday evening, the US had recorded 13,522,247 coronavirus cases and 267,844 deaths, both by far the worst tolls in the world.
Losers of US presidential elections traditionally concede almost immediately.
Biden said that in his first 100 days in office he will tackle the Covid crisis.
Globally, more than 60 million infections and 1.4 million deaths have been recorded since the new coronavirus emerged in China late last year.
The bonds will not affect students or travelers from fellow developed countries who are exempt from visas to enter the United States.
As more members of his Republican Party came out demanding an end to the impasse, Trump signed off on the GSA move, effectively admitting defeat.
The sudden break in Trump's dogged attempt to deny Biden's win came after Michigan became the latest state to certify its results.
Trump's refusal to concede has raised concerns that he could cause long-term damage to Americans' trust in the voting system
Rudy Giuliani, brazenly accused Democrats of being "crooks" who committed massive fraud in several battleground states.
Last year, Trump's administration made the controversial to decision to recognise Israeli sovereignty over the Golan.
It was not immediately clear if Trump, wounded by his election loss to Joe Biden, would take part in the summit or send a high level delegate in his place.