As we want to calculate the correlation between clinical and wastewater data over a period where they are supposed to be similar and thus where the WWI is supposed to mainly capture a majority of people also likely to be diagnosed , we decided to focus on the period corresponding to the second and third waves of the epidemic in France . To avoid being biased by the movements of individuals during the 2020 summer vacations , we consider the start date of the second wave as September the 1st , 2020 , from which the majority of holidaymakers returned to their residence city . We consider that the last point of the interval of interest is the date from which the signal undergoes a new growth phase following the decay of the second peak of the epidemic .