Christian AlthausKonto zweryfikowane

The figure (in German) shows the relationship between the reproduction number and the time in which the number of new #SARSCoV infections double (red) and reduce by 50% (green). (2/n)

In early March 2020, the virus spread uncontrolled in Switzerland with a reproduction number of 2.8 which corresponds to a doubling time of 3 days. (3/n)

During the 'lockdown' from March to May 2020, the reproduction number dropped to around 0.7 and the number of new infections were reduced by 50% every 9 days. (4/n)

During summer, the reproduction number was around 1.1 and the number of new infections doubled roughly every 4 weeks. (6/n)

With the beginning of autumn and the collapse of contact tracing, the reproduction number increased to 1.6 and the number of new infections doubled every 7 days. (7/n)

Switzerland introduced nationwide measures with strict upper limits on gatherings on 28 October 2020. This resulted in a drop of the reproduction number below the critical threshold of 1. Per 2 November 2020, the reproduction number was around 0.9. (8/n) https://ibz-shiny.ethz.ch/covid-19-re/ 

But just as a reproduction number of 1.1 led to a slow growth of the epidemic during summer, a reproduction number of 0.9 is not sufficient to rapidly reduce the number of new infections. (9/n)

Hence, it is critically important to reduce the reproduction number to 0.8 or less which would allow to reduce the number of new infections by 50% every two weeks. An adaptation in behavior and of current measures should allow to reach this goal. (10/n)

This would allow Switzerland to continue with a reproduction number around 1 throughout the rest of the winter after January, without the massive costs to health, the economy and the society. (11/n)

But still: There are close to 100 #SARSCoV2-related deaths per day and Switzerland has to expect at least 3,000 deaths for this 'second wave' by the end of the year. (12/n)