The percentage of molecular biological tests for diagnosis of COVID-19 is highly variable between different countries all over the world with multiple variations of these countries in size and distribution of targeted localities.

I did not see any information about that. So I think it is important to know how much you should randomly test in such new pandemic in order to be able to evolve your public health measures of control more efficiently. For example I am living in Malta (a small Island in the Mediterranean) which can be smaller than just one city in Germany (like Berlin), so in this case what is the lowest number of testing which can be considered satisfactory according to WHO and international Guidelines? Malta population are about 500,000.