Listener questions answered. How does blood type affect a COVID-19 infection? When in the recovery process does a sick person's contagiousness end? How many people need to be exposed to a virus for herd immunity to become possible?

What should you do if you’re worried you might have COVID-19? How do you help a relative who might have it? An episode with personal stories and care priorities.

Listener questions answered. Plus: is the cure worse than the disease? Business leaders and the president say so; Thomas Friedman says so; epidemiologists say not. Jonathan, Jonah, and Brian analyze the arguments. Recorded on March 23, 2020.

On quarantines, the strange presidential address of March 11, and pandemonium in markets. Recorded March 12, 2020.

If you consider actual infections and not merely confirmed cases, how many people have COVID-19 worldwide and how many in the USA? Also: what have we learned from the outbreaks on cruise ships? Recorded March 10, 2020.

Continued discussion of the outbreak in China. Plus: Are viruses alive? What is a virus (at the molecular level)? How is the new coronavirus distinct from other coronaviruses? What is the history of coronaviruses? Jonathan and Jonah offer an introduction to pathogenicity, lethality, and transmissibility, in general and as applied to COVID-19. Brian tries to stump them by asking if they can pair COVID-19 with a single optimistic thought. Recorded March 9, 2020.

How did Jonathan know in mid-January that this would be a pandemic? Other topics: What is a coronavirus? Where did the new virus come from? Are viruses alive? Also: Modeling the disease; modeling social responses; comparing the Chinese model, the Korean model, and the Iranian model of disease response. Recorded Monday, March 9, 2020.

Brian U. is joined by Jonathan Stevens and Jonah Keegan in discussion of world plagues; a threat that knows no bounds. Edited by Laura Jackson.