Before revision:  This puts forward the percentage of positive tests as a robust indicator of epidemic dynamics in absence of country-specific information. We next demonstrated this strongly affects data interpretation. Notably absolute case numbers trajectories consistently overestimated growth rates at the beginning of two COVID-19 epidemic waves. Overall, this supports non-trivial testing mechanisms can be inferred from data and should be scrutinized .
After revision:  This puts forward the percentage of positive tests as a robust indicator of epidemic dynamics , however we find it is subject to a saturation phenomenon that needs to be accounted for as the number of tests becomes larger .