Advisers to the Food and Drug Administration  meet this week to assess the safety and effectiveness of two Covid-19 vaccines. This is a major step toward approval and distribution of the drugs.  The first Americans, mostly health care workers, could start to receive the shots before the end of 2020. But public health officials warn it will take months before doses become widely available.

There will also be enormous hurdles to overcome along the way with distribution, but also convincing the public that this vaccine is safe.

Diane asked virologist Dr. Angela Rasmussen on the podcast to address some of those questions safety questions and clarify how the vaccine works. Dr. Rasmussen is an affiliate at the Georgetown Center for Global Health Science and Security.