A study by French scientists which suggests a man was infected with Covid-19 as early as 27 December, nearly a month before France confirmed its first cases, could be important in assessing when and where the coronavirus emerged, experts have said.
French researchers led by Yves Cohen, head of resuscitation at the Avicenne and Jean Verdier hospitals, retested samples from 24 patients treated in December and January who had tested negative for flu before Covid-19 developed into a pandemic.
The results, published in the International Journal of Antimicrobial Agents, showed that one patient – a 42-year-old man born in Algeria, who had lived in France for many years and worked as a fishmonger – was infected with Covid-19 “one month before the first reported cases in our country”, they said.
The World Health Organization said the results were “not surprising”.
“It’s also possible there are more early cases to be found,” WHO spokesman Christian Lindmeier told a UN briefing in Geneva.
He encouraged other countries to check records for cases in late 2019, saying this would give the world a “new and clearer picture” of the outbreak.
Independent experts said the findings needed more investigation.
“It’s not impossible that it was an early introduction, but the evidence isn’t conclusive by any means,” said Jonathan Ball, a professor of molecular virology at Britain’s University of Nottingham.
Stephen Griffin, an expert at the University of Leeds’ Institute of Medical Research, said it was “a potentially important finding”.
Cohen told French television on Monday it was too early to know if the patient, whose last trip to Algeria had been in August 2019, was France’s “patient zero”.
The researcherss said the absence of a link with China and the lack of recent travel “suggest that the disease was already spreading among the French population at the end of December 2019”.
France, where almost 25,000 people have died from Covid-19 since 1 March, confirmed its first three cases on 24 January.