Coronavirus may have been circulating in Italy in October 2019, according to more research that casts doubt over the true origin of Covid.
China didn't alert the world about the mysterious virus circulating in Wuhan — the city at the centre of the pandemic — until December 2019.
Beijing officials have insisted the virus originated in mid-December. But a mountain of studies have since poked holes in the claim.
Now, re-testing of dozens of blood samples of Italian patients suggest the infection was widespread in Italy months before anyone knew about the virus.
Results showed the blood of one cancer patient — originally taken in October 2019 — contained Covid-fighting antibodies.
Experts said their finding 'is a plausible signal' the virus was circulating much earlier than previously thought but said other evidence is needed to prove it.
Only low levels of the antibodies were spotted, making it hard to conclude that the patients definitely had Covid at the time.
Scientists in Milan admitted the findings may have been false positives, and experts not involved in the study suggested the other coronaviruses in circulation at the time may have triggered the immune response.
Covid didn't officially reach Europe until February last year — but the true timings of the pandemic remain under heavy scrutiny.
A debate is also raging over the source of Covid, with China repeatedly insisting the virus naturally spilled over into humans from bats. But observers claim it's possible the virus somehow leaked from the high-tech laboratory in the centre of Wuhan.
While China has tried to insist the virus originated elsewhere, academics, politicians and the media have contemplated the possibility it leaked from a high-level biochemical lab in Wuhan - raising suspicions that Chinese officials simply hid evidence of the early spread
Academics at Istituto Nazionale Tumori initially screened blood samples from 959 patients to check for lung cancer.
They re-tested the same samples last year to look for traces of the virus, and found 111 did contain Covid antibodies.
The World Health Organization subsequently asked them to reanalyse the samples, the Financial Times reports.
Experts sent 29 of the samples — some of which were positive — to VisMederi lab in Italy, which is affiliated with the WHO, and Erasmus University in the Netherlands.
Researchers then compared the results against a similar number of control samples taken in 2018.
Academics at VisMederi and Erasmus both found three of the samples to be positive for IgM Covid antibodies — which often crop up within days of someone becoming infected.
