Reactive testing in schools aims to avoid the systematic closure of classes when a case of COVID-19 is detected, by isolating only confirmed cases identified during two successive rounds of testing (Day 0 and Day 7). The pilot program described here was conducted in ten departments over two periods. A first two-week period before the fall 2021 break and a second three-week period after the break. The SARS-CoV-2 genome was detected via PCR analysis of saliva samples. Community incidence rates were moderate in Period 1 and high in Period 2. The first round of testing (Day 0) was conducted for 79% of the classes that had a reported index case in Period 1 (277 classes) and 39% in Period 2 (388 classes). This decline in the implementation rate reflects the difficulties encountered in implementing the protocol as the number of affected classes increased, in line with the significant rise in incidence among the general population. The two-day timeframe between case reporting and the return of results was met in 88% of classes in Period 1 and 74% in Period 2. The decline in this indicator also reflects the challenges encountered on the ground. When the protocols were first implemented, there was strong compliance among parents and children, and this compliance increased in Period 2 since, in classes where the first round of testing was conducted, 75% of students had been tested in Period 1 and 82% were tested in Period 2. In Period 1 and during the Day 0 screening, 1.9% of tested students were positive, and in 79% of the classes, all students were negative. Infections increased only slightly during the Day 0 screening in Period 2 (2.5% of students positive, 75% of classes entirely negative). Similarly, the number of detected infections did not increase during the second round of testing (90% of classes were entirely negative on Day 7 in Period 1, 89% in Period 2). The increase in community transmission of the virus was therefore not accompanied by an increase in the number of primary or secondary cases in schools. Schools do not therefore appear, under current conditions, to be sites of massive amplification of viral circulation. However, the second round of testing on Day 7, which aims to identify cases still in the incubation period on Day 0, made it possible to identify cases and clusters, justifying the importance of conducting it. The pilot program prevented the closure of 58% of classrooms in Period 1 and 26% in Period 2. The decrease observed in Period 2 is due to a reduction in testing rates and not to an increase in cases within classrooms. Contact tracing outside the classroom is important because it helps identify cases.