On 27 December last year, a 43-year-old man from Bobigny, a suburb of Paris, turned up at a French hospital with a dry cough, fever and trouble breathing. He had been sick for 15 days and had infected his two children, but not his wife, Dr Yves Cohen.
As part of a series of tests, doctors had originally collected samples to check for the flu using a polymerase chain reaction test — the same test used to detect the new coronavirus — which searches for bits of viral genetic material.
Instead, what they discovered months later, was that a sample taken just after Christmas tested positive for COVID-19.
The man had, therefore, contracted the virus nearly a month before France confirmed its first cases. But it's still not clear how he was infected, as he hadn't recently travelled.
Doctors can't say whether or not he was France's "patient zero."
This case is part of ongoing evidence that COVID-19 has been with us all much longer than we first thought. Genetic analyses of the new coronavirus suggest that the virus emerged in humans in China in late November to early December 2019. While China’s official submission to the World Health Organisation (WHO) states that the first infection was recorded on 8 December, government data seen by the South China Morning Post newspaper seems to suggest that the first known case was actually observed on 17 November.
Anecdotally, we have all heard stories of friends or relatives who came down with severe flu in the winter, presenting many of the symptoms now associated with coronavirus, but most of them have not yet been tested.
But if that evidence is confirmed, it leads to an obvious question: why, then, did we suddenly see a peak in cases in different countries at different times? Why did the number of cases seemingly explode?
Smouldering under the surface
Well, theories abound. One is that not everyone is equally infectious and so carriers don't have the ability to spread the virus equally. Also, it is likely that most of those early cases will have been so ill, bedridden, that they would have isolated anyway, suppressing contact with others and so slowing the spread of the disease.
Another possibility, says Nathalie MacDermott, clinical lecturer in infectious diseases at King’s College London, is that the virus was “smouldering under the surface for a long time and we weren’t necessarily identifying it."
"The elderly population, generally speaking, are a little bit less likely in the first place to come into contact with it, because they are not in a workplace where they are having frequent contact with people," she told The Guardian newspaper. "They go out, but it might be more limited… so maybe it took a while to get to widespread community transmission and to start affecting our older population.”
Ultimately, even if there was transmission earlier than we first thought, that doesn’t mean that most of us have had the virus or, indeed, are immune to it. As I’ve remarked before, early analysis recently published by the Spanish government involving 60,000 people showed only 5 per cent of the Spanish population has so far been infected. In France, it was only 4.4 per cent.
There are still so many things we don’t know about this novel virus, COVID-19, and about its transmission. But by trying to understand the first cases and their spread we might get a sense of what the future might hold.
Darren McCaffrey is Euronews' political editor.