The wastewater samples indicate a strong increase in the circulation of the Omicron variant in Italy in the three weeks between 5 and 25 December. These are the results of the extraordinary Flash survey on Omicron, which analyzed 282 wastewater samples collected in 98 sampling points from 16 regions and autonomous provinces. In total, 80 samples (28.4%) were identified as positive for the Omicron variant by a rapid molecular test developed by the Istituto Superiore di Sanità.
Consistent growth trend
Over the 3 weeks, in agreement with the epidemiological picture, a considerable trend of growth of positivity in the samples was observed. Between 5 and 11 December there was 1 positive sample out of 74 (one region). Between 12 and 18 December 15 positive samples out of 108 (7 regions). Between 19 and 25 December, 64 positive samples out of 100 (14 regions). In the week of December 19-25, the presence of the variant underwent a significant increase in the national territory (Abruzzo, Campania, Emilia Romagna, Lazio, Lombardy, Marche, Piedmont, Puglia, Sicily, Tuscany, Umbria, Veneto, autonomous province of Bolzano, province autonomous of Trento). The integration of these data, with those coming from epidemiological surveillance, will allow to accurately monitor the evolution of Omicron, and of other variants.
La Rosa: “Fundamental surveillance to understand the evolution of the pandemic”
The study was carried out by the working group coordinated by Giuseppina La Rosa of the Environment and Health Department and by Elisabetta Suffredini of the Food Safety, Nutrition and Veterinary Public Health Department of the ISS, with the collaboration of the SARI network, national surveillance of SARS- CoV-2 in wastewater. “The environmental surveillance of Sars-Cov-2 in waste water – commented Giuseppina La Rosa -, implemented in Italy from October 2021 following the Commission Recommendation (EU) 2021/472 of March 17, 2021 and the decree law May 25, 2021 , no. 73, a fundamental tool is emerging, complementary to epidemiological surveillance, to understand the evolution of the pandemic “.