In epidemiology, the basic reproduction number (sometimes called basic reproductive ratio, or incorrectly basic reproductive rate, and denoted R0, r nought) of an infection can be thought of as the number of cases one case generates on average over the course of its infectious period, in an otherwise uninfected population. Watch this latest update on the corona virus to see how it appears most likely that this virus has a R0 above 4 which is absolutely massive. If you are not yet prepared get cracking this is no joke!