In Oct 2020 some friends had spent 2 weeks touring Italy. They felt fine and had a good, uneventful trip. On the return flight back to the USA, one of them started feeling ill, like a cold. Within 24 hours they were admitted to a major hospital here in the States with double pneumonia, high fever, and failing kidneys. Mind you only one had taken ill, the other never should any signs/symptoms. Italy reported a superbug going around at that time. In retrospect my friend thought they might have already had covid-19 so they went to get tested but it was 6-7 months later and it did not show. To this day they still think it was COVID-19.
At the time of your friends’ travel, there were direct flights between Wuhan and northern Italy. Most of that region’s high end fashion production relied on the labor of illegal Chinese immigrants from Wuhan. It is suspected that is how COVID first got to Italy and Europe.