THE INITIAL AND DAILY COVID-19 EFFECTIVE REPRODUCTIVE NUMBER IN SOUTH AFRICA
This report includes an analysis of data on laboratory-confirmed COVID-19 deaths to estimate the effective reproductive number (R) of SARS-CoV-2 over time in South Africa nationally and in selected provinces where sufficient data are available. The effective reproduction number (R) is the average number of secondary cases per infectious case in a population composed of both susceptible and nonsusceptible hosts (once the infectious agent is circulating).
-During the stage 3 lockdown, the daily R varied slightly, with an average of 1.05 (95%CI: 1.01 – 1.09), between 1 June and 1 August, dropping below 1 during the last weeks of July. This indicates ongoing transmission at a steadily slowing rate over this period, with numbers of new cases per infectious case dropping below 1 towards the end of the period.
-In provinces where estimation was possible for stages 5, 4 and 3 (Western Cape, Gauteng, Eastern Cape and KwaZulu-Natal provinces), the R during the stage 5 and 4 lockdown ranged between 1.5 and 1.0. Generally, R showed reductions during the stage 3 lockdown indicating slowing of transmission in all three provinces by the end of July
-This report includes new estimates of R during the stage 3 lockdown for Mpumalanga and Free State provinces, indicating steady declines in R over this period.