EPIDEMIC: The incidence rate in the Charente was halved. But the number of coronavirus Covid-19 tests carried out also
A spectacular drop in the incidence rate of the coronavirus Covid-19 in Charente. From 243 / 100,000 inhabitants during the peak of March 29, to 120 / 100,000 inhabitants on April 29! Or a halving of this indicator, scrutinized like milk on the fire by public decision-makers. Sacred perf. Thank you for the confinement? The reality is much more nuanced.
Because over the same period, the number of tests carried out in the department was also halved. 14,258 Charentais were tested the last week of March. And for the latest consolidated figures, which concerns the week of April 19 to 26, there were “only” 7,538 tests.
However, the incidence rate is “the number of people declared positive in a territory” reduced to 100,000 inhabitants. The more tests you do, the more likely you are to detect positive people. The converse being true.
If it looks like good news, the displayed drop in the incidence rate must therefore be handled with infinite caution. Even tweezers.
Because over the same period, the positivity rate – that is to say the percentage of positive tests – is at the stall: around 6% in Charente, with a peak at 7.5% in mid-April. A variable which suggests that if we had done as many tests at the end of April as at the end of March, the incidence rate would be… the same. Here again, a qualification to be made: the positivity rate depends on the population tested. There were several massive testing campaigns at the end of March – in Châteauneuf, Soyaux, in schools – which tends to “dilute” the positivity rate.
Another gloomy indicator: there are still 59 people hospitalized because of Covid in the Charente establishments.
