Around a hundred guests gathered for an office Christmas party in Norway last Friday—now officials think it’s the source of the nation’s raging outbreak of the heavily mutated Omicron coronavirus variant. According to The Local, every party guest was vaccinated and they all took tests before they gathered for the party in Oslo. “So far 60 [attendees] have tested positive with PCR tests, and four with antigen tests,” the city of Oslo reportedly said in a statement. “Seventeen are probably Omicron, but that has yet to be confirmed. So far, one case is confirmed to be Omicron after sequencing.” Oslo health official Tine Ravlo told AFP: “All of them had been vaccinated, none of them had symptoms, and they had all done self-tests... Everything was done in line with regulations and no rules were broken.” One of the guests had reportedly traveled to southern Africa, where the variant was first identified. The good news is that, according to Ravlo, the infected guests are displaying mild symptoms.