Test, Test and Test: Understanding COVID-19?

The world is saying “test, test, test”. So why should we test? Well, apart from finding out those that may need help, we also need to understand how much of the population is infected at any time, and use this to understand the spread (and decay) of the virus. Without this we are basically seeing a lag of many weeks (or months), and where it will be too late to understand how the virus is spreading. Without testing, our model simply becomes counting those who have sadly died and then trying to work backwards.

Overall I have found the data available on COVID-19 rather weak from a scientific point of view. But Kai Sasaki is one researcher who has implemented an SIR (Susceptible, Infection and Recovered) model. It is focuses on the Kermack-McKendrick model and which was proposed in 1927, and then re-defined in 1979 [here]:

The SIR model aims to identify those who are susceptible to a disease, those who are infectious, and then those who have recovered. Basically it measures the rate at which those are are susceptible to become infectious (β), and the rate at which those who are infectious actually recover (γ):