WHO studying evidence of coronavirus antibodies found in Italy dating back to late 2019 (2)

A man wearing a face mask walks past the Pantheon in Rome, Italy, April 21, 2021. (Xinhua/Cheng Tingting)

Though Erasmus University Rotterdam did not immediately reply to a request for comments, Montomoli told Xinhua the university lab's conclusions "were very similar to what (Italy's National Cancer Institute) discovered, though there were some small differences."

Montomoli said the combined results "made a very convincing case" that the coronavirus or a similar virus was in circulation in Italy months earlier than the country's first officially recorded COVID-19 case in February 2020.

"We did not find evidence of the virus but rather of the antibodies an infection leaves behind," Montomoli said. "The only way for that to be the case was for the coronavirus or something very similar to have infected these people in late 2019. It's possible it was the same virus that had been found in Wuhan in December (2019) or perhaps it was a less serious and less transmissible variant."

At the time the results of the study were released, Giovanni Apolone, scientific director of the institute, said the findings did not cast doubt on the origins of the virus but do call into question the timing.