BEIJING, Nov. 22 (Xinhua) -- As COVID-19 disrupts the lives of tens of millions across the world, one question remains elusive: where did the virus come from?
In Italy, according to a study released by the National Cancer Institute (INT) in Milan, the coronavirus may have been circulating in the country since September 2019.
If true, it would mean that the virus was present in Italy three months before it was first reported in China in December 2019, and five months before the first official case was recorded in Italy on Feb. 21, 2020.
The INT research showed that 11.6 percent of the 959 healthy volunteers who participated in a lung cancer screening trial between September 2019 to March 2020 had developed COVID-19 antibodies well before February.
Giovanni Apolone, a co-author of the study, said, "we found positive cases had been present in the months before the first case was reported in China at the end of December 2019, and before the first case was reported in Italy on February 21, 2020. We found cases in September, October, November and December of 2019."
The northern region of Lombardy, whose capital is Milan where the pandemic first emerged in late February, had previously reported an unusually high number of cases of severe flu and pneumonia in the last quarter of 2019 in a sign that COVID-19 may have circulated earlier than previously thought.
Apart from Italy, there have also been other reports about the virus being discovered elsewhere earlier in 2019.
Spanish virologists discovered traces of the novel coronavirus in a sample of Barcelona waste water collected in March 2019, nine months prior to the virus outbreak in China.
And in Brazil, a study detected the coronavirus in human sewage in Santa Catalina, Brazil, in samples collected in Nov. 2019.
A World Health Organization (WHO) regional official said the novel coronavirus could have existed in a dormant state long before its outbreak.
"This virus lived in animals and at some point passed to humans. It's hard to say when and where this happened. It's being investigated. Viruses can be found in waste water. But nothing can be said specifically," said Melita Vujnovic, representative of the WHO to Russia, in an interview with RIA Novosti news agency.
According to Tom Jefferson, a scientist at the Centre for Evidence-Based Medicine at Oxford, the novel coronavirus has existed worldwide and broke out whenever and wherever favorable conditions occurred rather than starting in China.