COVID-19 was already circulating in Italy in December 2019, reveals sewage study

A new study has revealed that the novel coronavirus was already circulating in northern Italy before China reported the first cases as scientists in Italy have found traces of COVID-19 in wastewater collected from Milan and Turin in December 2019.

The Italian National Institute of Health looked at 40 sewage samples collected from wastewater treatment plants in northern Italy between October 2019 and February 2020. An analysis released late on Thursday said samples taken in Milan and Turin on December 18 showed the presence of the SARS-Cov-2 virus, over two months before the first case was detected.

Italy has reported more than 2,38,000 cases, with over 34,500 deaths.

"This research may help us understand the beginning of virus circulation in Italy," Giuseppina La Rosa, an expert in environmental wastewater at the Italian National Institute of Health who co-led the research, said in a statement detailing the findings.

Italy's first known native case was discovered mid-February.

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, Reuters reported.

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 December 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.

More than 8.4 million cases of the novel coronavirus have been confirmed worldwide, including at least 453,000 deaths, according to a Johns Hopkins University tally.