Coronavirus

In a vast game of chance and competition, things can get ugly

Whenever there’s a new outbreak, scientists rush to calculate a number called R₀, or R-naught. Why? It’s been a critical part of the scientific effort to understand just how transmissible the new virus is. Here’s how.

Editor’s Note (2/11/20): The video in this story has been revised after posting. It originally incorrectly referred to SARS as “sudden acute respiratory syndrome.” The full name is “severe acute respiratory syndrome.”

Infection’s spread is still limited, although cases have nearly tripled in past two months