Aim To describe the trends of RT-PCR positive SARS-CoV-2 rates in children and adults according to the time of COVID-19 epidemic. Methods In this prospective multicenter study involving 45 pediatric units, we collected the results of nasopharyngeal swabs in France from March 2, 2020 to April 26, 2020. Results During the study period, 52,588 RT-PCR tests for SARS-CoV-2 were performed, 6,490 in children and 46,098 in adults. The rate of positive tests for children was 2- to 7-fold less than that for adults. These rates varied according to the time of the epidemic and were higher at the peak. The lower rates of positive test in children persisted during the surveillance period but varied according to the time in the epidemic. Conclusion The rate of positive RT-PCR positive SARS-CoV-2 tests for children was always less than that for adults but vary according to the epidemic stage.