Officially, France's first confirmed COVID-19 case was a traveler from China. Yet, geneticists at the Institut Pasteur argue the virus was already spreading locally by mid-January 2020—before the major outbreak. Here's the evidence.
France's first official COVID-19 case was an 80-year-old man from China's Hubei province, arriving in Paris on January 23, 2020. The epidemic grew slowly: by February 17, only 12 cases were reported, mostly imported.
However, Institut Pasteur researchers, in a study posted on bioRxiv on April 24, 2020, suggest the virus circulated freely from mid-January. Asymptomatic or mildly symptomatic individuals likely carried it weeks before March's wave.
Surveillance began January 10. Europe's first three imported cases were detected in France soon after. Initial strains sequenced from January 23-29 traced to Wuhan; later ones linked to Italy.
The study analyzed 97 viral strains collected up to March 24, 2020, incorporating global sequences. This revealed low genetic diversity among French variants, clustering them in the "G lineage."
These early variants have since faded due to isolation measures. Most circulating strains share this G lineage profile.
Institut Pasteur holds one of Europe's earliest G lineage strains, from February 19 in Oise department—from a patient with no travel history or known contacts. This points to local, undetected spread in Oise and likely elsewhere by mid-January or early February.
Note: This preprint on bioRxiv awaits peer review, and findings may evolve with more data. French regions were not fully represented. Still, researchers estimate 95% of strains belong to the G lineage, indicating local transmission chains over imports.
