How contagious is the Delta Covid variant? Take charge of this interactive and watch how small changes in isolation or reproduction rates of Covid-19 can affect our battle against it.

One important characteristic of viruses and other pathogens is how contagious or infectious they are. One key measure of this is the R0, or basic reproduction number, which indicates how many new cases one infected person generates.
For an R0 of three we would expect each new case of a disease to produce three other infections.

This is not just a measure of the inherent infectiousness of a disease. It also depends on other factors, including the rate of contact within a population and the duration of the infectious period. It’s a situation-dependent value, so in one city the R0 might be higher and in another lower. It also assumes that the entire population is susceptible to the disease.

So what does the R0 of Covid look like, and how does it compare with other diseases?