What is the ‘R’ Number

What is the ‘R’ Number

The ‘R‘ number is a way of rating a disease’s ability to spread. It refers to the reproduction number of an illness, and represents the average number of secondary infections produced by 1 infected person. R is one of the most important things you can track to understand an epidemic and facilitates better planning for potential interventions to combat the virus. The R number is of greater significance when there are large numbers infected. 

R is estimated by a range of independent modelling groups based in universities and Public Health England (PHE). For more information on ‘R’, click here.

An R number of 1 means that on average every person who is infected will infect 1 other person. If R is 2, it means that on average, each infected person infects 2 more people; if R is 0.5 then on average for each 2 infected people, there will be only 1 new infection.

The R number can change over time; for instance, it falls when there is a reduction in the number of contacts between people – this reduces transmission.

If the R is higher than 1 that means this disease is growing exponentially and will keep on spreading to more and more people. In order to keep R below one and control the virus, it is crucial that people stay alert and continue to follow the latest government guidelines and Public Health advice.