Small studies conducted by scientific teams in the Netherlands, France, Australia and elsewhere have found signs that the virus that causes COVID-19 can be detected in sewage, and many countries are beginning to use wastewater sampling to track the spread of the disease.
La Rosa said the detection of traces of the virus before the end of 2019 was consistent with evidence emerging in other countries that COVID-19 may have been circulating before China reported the first cases of a new disease on Dec. 31.
A study in May by French scientists found that a man was infected with COVID-19 as early as December 27, nearly a month before France confirmed its first cases.
La Rosa said the presence of the virus in the Italian waste samples did not "automatically imply that the main transmission chains that led to the development of the epidemic in our country originated from these very first cases".
Samples positive for traces of the virus that causes COVID-19 were also found in sewage from Bologna, Milan and Turin in January and February 2020. Samples taken in October and November 2019 tested negative.
The institute said it plans to launch a pilot study in July to monitor wastewater at sites identified in tourist resorts.