There continue to be studies in test tubes and lab rodents which all show pretty convincingly that Omicron does not infect the lungs as well as previous versions.
This preprint says that T cells from vaccination still have 70-80% of their protection against Omicron (which is probably why breakthrough cases are mild).
This preprint says that people with Omicron are more often asymptomatic than people with other variants.
This thread talks about why the US CDC’s guidance that people only need to isolate for five days is a baaad idea. (They really like the UK’s way of testing on day 6 and day 7 to leave isolation, on the other hand.) Among other things, they point to this paper which shows that lots of people keep shedding virus after five days:
This preprint says that there are several coronaviruses in European and African bats which are very very close to being able to jump to humans.