[Sephiroth]

Poor old jfman! At 0.5, the factor is applied only to the number of new cases not the original total. But no matter, the series leads to an almost complete defeat of the virus providing it can be maintained. The time it takes to do this is for the statisticians and epidemiologists to tell us but at its simplest, using a two week window, it would take a year for the number of new case to dip below 100 starting with 1 million.

To put that into UK perspective, if you started with 250,000 cases then R=0.5 would still take around 24 weeks to dip below 100.

If R=0.7 then it would take 46 weeks to dip below 100.

BUT - nobody knows the real R rate nor how to fix it to within reasonable margins of error.