Much remains unknown about Omicron. It has gained a foothold in Asia, Africa, the Americas, the Middle East and Europe, where a fifth wave of the pandemic and surging infection numbers are fast draining any sense of festive cheer.
Evan as scientists race to understand how contagious and virulent the Omicron variant is, the experience of Seine-en-Bateau illustrates how companies are acting even before policy-makers in some countries impose new curbs.
The increasingly cautious mood deals a blow not just to bars and restaurants, but the wider entertainment industry.
Ben Soussan said Seine-en-Bateau charges tens of thousands of euros for a full-blown party for several hundred people. "It's the whole chain that is impacted: caterers, DJs, magicians, interior decor workers."
An increasingly bleak picture is emerging across Europe.
Highlighting the risks, Norwegian authorities said 13 people had been infected with the Omicron variant following a corporate Christmas party in Oslo.
British supermarket group Sainsbury's said it had postponed all Christmas parties until the new year while JPMorgan cancelled its annual festive carols reception in London, citing the pandemic. JPMorgan also said it was postponing indefinitely its year-end party in Paris.
Deutsche Bank has told its London staff they can hold small gatherings at the individual team level, with a negative lateral flow test required. Asset manager Schroders and the City of London Corporation which runs London’s historic financial district also asked guests to take rapid tests before attending particular festive events.
"Are companies willing to take responsibility for the welfare of their employees or do they think the risk is acceptable" said one manager at a consultancy in London, who declined to be named to avoid identifying their employer.
British Prime Minister Boris Johnson has repeatedly insisted people should not cancel their holiday celebrations, though senior health official this week said people should not socialise unless necessary.
French President Macron is convening senior ministers for a COVID-19 'defence council' on Monday but has so far made clear he favours accelerating vaccine boosters over curbs. The German government has not yet issued any recommendations for the festive period.
In Germany, nine out of 10 restaurants and event locations had reported Christmas party cancellations by mid-November, according to hospitality body Dehoga. It estimates nearly half of Christmas parties have been called off so far.
Back in Paris, singer and DJ Severine Nells said her December, which two weeks ago was set to be as busy as in 2019, was fast unravelling as last minute cancellations came in. Clients were also heaping doubt on provisional January bookings.
"I was supposed to be working tonight. But (the client) pulled out two days ago," Nells said. "It's the companies making the decision because they're afraid.
(Reporitng by Richard Lough in Paris and Iain Withers and Carolyn Cohn in London; additional reporting by corporate finance teams, Gwenaelle Barzic in Paris and Klaus Lauer and Rene Wagner in Berlin; Editing by Emelia Sithole-Matarise) ((Email: firstname.lastname@example.org; Tel: +33 1 80 98 12 45 ;))