The “resurgence” has been observed since 25 June, with a “sharp increase in…concentration” particularly in the south of the grand duchy, while “only samples from the Troisvierges site appear negative.”

Levels of RNA concentrations of the virus have nearly tripled at wasterwater treatment facilities in Petange and Bettembourg, while the authors note that sites in the north of the grand duchy and in Hesperange “are seeing a lower and more stable concentration over time,” with a caveat: “the method still needs to be refined in order to clarify the significance that can concluded from small amplitude variations in Sars-CoV-2 RNA concentrations.”

In the Coronastep initial findings, it was reported the virus has been in circulation in the grand duchy since 25 February. The wastewater study is “an effective pre-alert system of virus resurgence in the population”, according to List.