By Giselda Vagnoni and Emilio Parodi
ROME (Reuters) - An Italian study supporting the case that the novel coronavirus was circulating outside China earlier than thought has sparked doubts among some Western scientists who called for further tests.
A paper published by the Italian Cancer Institute (INT) describes the presence of neutralizing antibodies to SARS-CoV-2 in blood taken from healthy patients in Italy in October last year during a lung cancer screening trial.
If the data are correct, they would change the history of the pandemic and raise questions of when and where the virus emerged. It was first identified in the central Chinese city of Wuhan in December.
But several scientists interviewed by Reuters said further examination was needed.
"These results are worth reporting, but mostly should be taken as something to follow up with further testing," said Mark Pagel, professor at the School of Biological Sciences at Britain's University of Reading.
"All of the patients in the study were asymptomatic despite most being 55-65 years old and having been smokers. This would normally be a high-risk group for COVID-19, so it is puzzling why all patients were asymptomatic."
A co-author of the study said he and his colleagues were planning further investigations and called for scientists worldwide to contribute.
The World Health Organization has said the new coronavirus and COVID-19, the respiratory disease it causes, were unknown before the Wuhan outbreak was reported. But it has said the possibility that the virus may have "silently circulated elsewhere" cannot be ruled out.
There have been at least 55,573,000 reported infections and 1,336,000 reported deaths caused by COVID-19 globally since the virus was first detected in China.
China believes the Italian study shows that tracing the origin of the virus is an ongoing process that may involve many countries.
"China will continue working with the rest of the international community to contribute to the global cooperation on fighting COVID-19 and other viruses,", Zhao Lijian, spokesman for the Chinese foreign ministry, told reporters in Beijing on Tuesday.
Italy's first COVID-19 patient was detected on Feb. 21 in a small town near Milan, in the northern region of Lombardy. But the Italian researchers' findings show 11.6% of 959 healthy volunteers enrolled in the cancer screening trial between September 2019 and March 2020 had signs of having already encountered the SARS-CoV-2 coronavirus, most of them well before February.
A further SARS-CoV-2 antibodies test was carried out by the University of Siena for the same research paper, called "Unexpected detection of SARS-CoV-2 antibodies in the pre-pandemic period in Italy".
It showed that in six cases, the antibodies were able to kill SARS-CoV-2. Four of the cases dated back to October 2019, meaning the patients had become infected in September.
"This number (six) is fully compatible with test errors and statistical noise. For these reasons, it seems to me that the evidence brought to support such an extraordinary claim is not solid enough," said Enrico Bucci, biologist adjunct professor at Philadelphia's Temple University.
"Much ado about nothing," Antonella Viola, professor of general pathology at the University of Padua, told Reuters.
'SERIOUS ISSUE INDEED'
Both Italian scientists said the antibody test was in-house designed and never validated by other researchers in a peer review.
What was also noticeable was the very high seroprevalence in the research study's population, they said, referring to the percentage of people who may have been exposed to the virus.
"For there to be an epidemic (albeit apparently asymptomatic) on this scale in Italy a full year before the current pandemic that went unnoticed would be a serious issue indeed," said Stephen Griffin, associate professor at the University of Leeds.
Most of the scientists' scepticism focuses on the so called specificity of the antibody tests, that, if not perfect, might reveal the presence of antibodies to other diseases.
"Other recent reports have shown that seasonal coronaviruses can elicit cross-neutralizing antibodies," said Jonathan Stoye, group leader at the Francis Crick Institute.
"I think we need a really conclusive demonstration that those samples are picking up the COVID-19 virus and that those antibodies were not actually triggered by another virus," Andrew Preston, reader in microbial pathogenesis at the University of Bath, told Reuters.
Preston said he was surprised that those requirements weren't needed for the publication of a research paper.
"But it is perfectly feasible to go away and do those extra tests and come back and show that," he added.
The INT's scientific director and co-author of the study is planning further investigation into the study patients' clinical history.
"We need to understand if they had symptoms of illness. Where they had gone, if they had contact with China," Giovanni Apolone told Reuters, calling for colleagues globally to "open their databases and conduct retrospective researches".
(Reporting by Emilio Parodi, Josephine Mason and Giselda Vagnoni. Additional reporting by Roxanne Liu in Beijing. Writing by Giselda Vagnoni; Editing by Nick Macfie)