LONDON (AP) —

French scientists say they may have identified a possible case of the new coronavirus dating back to December — about a month before the first cases were officially confirmed in Europe.

In a study published in the International Journal of Microbial Agents, doctors at a hospital north of Paris reviewed retrospective samples of 14 patients treated for atypical pneumonia between early December and mid-January. Among those were the records of Amirouche Hammar, a 42-year-old fishmonger from Algeria who has lived in France for years and had no recent travel history.

Hammar told French broadcaster BFM-TV on Tuesday that he drove himself to a hospital emergency unit at 5 a.m. one morning in late December because he felt very sick, with chest pains and breathing difficulties.

“They said, ‘Perhaps you have an infection, a pulmonary infection, although it’s not certain. But what you have is very serious, very serious, because you are coughing blood. It's not normal flu,’” he said.

Hammar was admitted to the hospital with symptoms doctors say were consistent with COVID-19 patients in China and Italy. When doctors retested his old sample, they found it was positive for the coronavirus.

“Identifying the first infected patient is of great epidemiological interest as it changes dramatically our knowledge” regarding the spread of the coronavirus, wrote Dr. Yves Cohen, one of the French researchers. An intensive care specialist, Cohen works in the northern suburbs of Paris where Hammar lives and which have been particularly hard-hit by COVID-19 infections and deaths.

There doesn't appear to have been any further transmission of the virus from Hammar, who later recovered. Cohen and colleagues suggested their results showed there could be many other unidentified coronavirus cases from before the disease was officially detected in Europe.

Still, the scientists acknowledged that because the study, which was published online Sunday, was done retrospectively, “medical records were not exhaustive and some relevant information might have been missing.”

Other experts said the results were interesting, but hardly conclusive.

Jonathan Ball, a professor of molecular virology at the University of Nottingham, said it was possible the results were due to lab contamination.

“If he was infected (with COVID-19), then you would expect a more rapid and earlier spread of the virus in France than was seen,” he said in a statement. Ball wasn't connected to the published study.

“Sequencing any virus in the sample might give you insight into whether or not the virus truly was an early isolate or likely contamination, but it looks from the data that the amount of virus in the sample was low, so would be difficult to analyse further,” he said.

Rowland Kao, an epidemiologist at the University of Edinburgh, said that even if the case was confirmed as COVID-19, it wasn't confirmation that the virus started spreading in Europe earlier than was believed.

“There are likely to be many instances where, around the world, infected individuals have moved to an uninfected location, but no transmission occurred,” he said.

Doctors in Italy have also reported finding retrospective cases of the coronavirus in the country long before the disease was officially identified.

John Leicester in Paris contributed to this report.

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