A new study from the National Cancer Institute (INT) of the Italian city of Milan has put forward potential evidence that Covid-19 may have been circulating in Italy long before China first reported about a cluster of pneumonia cases of unknown cause on December 31, 2019.
The pre-print study has yet to be peer-reviewed and was published by the INT's Tumori Journal. In order to track the spread of the virus across Italy, the team looked at the blood samples of 959 asymptomatic individuals enrolled in a prospective lung cancer screening trial between September 2019 and March 2020. They found that SARS-CoV-2 antibodies were present in 11.6 percent of the samples overall, with by far the highest number of positives coming from Lombardy (53.2 percent), which was hit hard in the early stages of the pandemic.
The real surprise (and remember the study is yet to be peer-reviewed) was that they found antibodies in patients from as early as September 2019. 14.2 percent of the volunteers had antibodies for the disease, with the first case found in someone from the Veneto region on September 3.
"Our results indicate that SARS-CoV-2 circulated in Italy earlier than the first official Covid-19 cases were diagnosed in Lombardy," the team concluded. "Even long before the first official reports from the Chinese authorities, casting new light on the onset and spread of the Covid-19 pandemic."
The team told Reuters their main finding was that "people with no symptoms not only were positive after the serological tests but also had antibodies able to kill the virus," adding that "coronavirus can circulate among the population for a long time and with a low rate of lethality, not because it is disappearing, only to surge again."
While the study is intriguing, there are reasons to be skeptical.
"There is evidence SARS-CoV2 was in circulation in Italy in December 2019 based on the analysis of wastewater," Professor Francois Balloux, director of the University College London Genetics Institute, wrote on Twitter. However, he believes that to say that the virus was circulating unnoticed in Italy as far back as August — which would be the case for the earliest volunteers to develop antibodies — they would need to produce much stronger evidence.
"Analyses of thousands of SARS-CoV2 genomes point to an origin (host jump into humans) in ~Oct/Nov 2019 in China, and a rapid spread to Europe," he wrote. "Irrespective of how we run the analyses, circulation in Italy in August is incompatible with the data."
The World Health Organization (WHO) told Reuters they would contact the paper's team to “discuss and arrange for further analyses of available samples and verification of the neutralization results."
