Input Parameter

Input Parameter Details

The reproduction number indicates how many others an infected person infects on average.

The positive rate controls the proportion of infected individuals in the population.

The sensitivity indicates the propotion of infected persons who actually receive a correctly positive test result after a test.

The specificity indicates the proportion of non-infected persons who receive a correctly negative test result after a test.

The test growth rate refers to the weekly percentage expansion of tests. The starting number of tests is set according to the test growth rate.
If the growth rate is set to 0, the number of tests is set to 1 million. If the test growth rate is set to 10%, the number of tests in the first week is set to 424,098. In that case, the number of tests, once again, amounts to 1 million after ten weeks.

Dynamics

Short Description

This app illustrates the differences between a test strategy with an increasing number of tests and a test strategy with a fixed number of tests.

If the test growth rate is set to 0, the number of tests is 1 million for every ten weeks. In that case the reproduction number and the incidence for the week ten can be estimated accurately. However, if the number of tests is not fixed, but is increased weekly, by e.g. 10%, the incidence is significantly overestimated. This is due to the fact that no differentiation is made between more positive cases as a result of the virus spreading in the population and more positive cases due to simply more testing.

Moreover this app can be used to explore the impact of tests of different quality (determined by sensitivity and specificity) on the infection dynamics.
According to the Paul-Ehrlich-Institut the minimum requirements for a corona test is a specificity of at least 97% and a sensitivity of at least 80%.