Biden's Covid team is nervous about what the Trump team hasn't told them

With the hours dwindling until Joe Biden is sworn in -- officially taking the helm of the US government during its worst health crisis in 100 years -- a sense of nervousness has set in among those advising the incoming President on the pandemic.

The overarching, nagging concern: "They don't know what they don't know," said a source close to the Biden Covid-19 team. Biden is set to inherit a nation grieving hundreds of thousands of Americans who have perished from the virus, a health care system buckling under the strain of the pandemic, new variants of the disease popping up around the world and a public that is both stressed about the prospect of when they can get vaccinated, as well as dubious about whether to trust the vaccine when it's their turn in line.