Since he was appointed to lead the Centers for Disease Control and Prevention in June 2009, Tom Frieden, the real-life equivalent of a health official in the movie Contagion, has taken many late-night phone calls. He's guided the agency through H1N1 swine flu, Ebola, and Zika outbreaks — just a few of the viruses that are spreading around the world faster and more effectively than ever before.

With President-Elect Donald Trump taking office this week, there's a lot of uncertainty about how the US will handle public health and respond to potential future pandemics. 

There's also uncertainty about what will happen to the CDC budget and vaccine coverage rates under a president who spreads vaccine conspiracy theories. And Frieden's own future is currently in limbo, as submitted his resignation as director on January 20.

But when we met Frieden at the CDC offices in Washington, DC, last week, he was optimistic.