Tracking the reproduction number R0(t) in Belgium in the period March 1st - July 20th
We investigate here the evolution of the reproduction number for COVID-19 to determine the rate with which the virus spreads in Belgium. We present a day-to-day evolution of an estimator that is in close agreement with publicly released figures and which indicates a steady increment for a sustained period of time.
The reproduction number R0(t) is a measure of the transmission capacity of the virus at a moment in time. It represents an average number of secondary infections that an infected person can produce in the population, where it is assumed every person is susceptible. Now that the start of the second wave in Belgium is more visible, it is of utmost importance to have a precise estimate for this transmission rate and to evaluate what the effects of the relaxation of the restrictions were with respect to the spread of the virus.
Today coincides with what would have been the fifth phase of relaxing restrictions, but it has quickly reversed to a phase where more localized, regional restrictions are enforced, due to the alarming increase in new infections on the Belgian territory. Our analysis shows that the increment in cases is not surprising as the reproduction number has been steadily increasing since the beginning of June. Moreover, the end part of June was the moment in time when the reproduction number surpassed the target value of 1, most probably the effect of the third relaxation phase combined with a less stricter compliance from the population with the sanitary guidance. With the current model we predict that at this moment in time, an infected person can create on average 1.3 secondary infections. Our models predict as well an increment in the infectious cases for the week to come, which will only maintain the reproduction number at higher values than the target.
More updates can be found here: https://eugenpircalabelu.shinyapps.io/covid19-forecasting/