Coronavirus Response Team's briefing in which Dr. Fauci spoke on the subject of getting together in groups over the Holidays...(the entire briefing text is attached)
"Now, one of the questions that Dr. Walensky and I and Dr. Murthy and others get asked very frequently is that, right now, as we get to the Christmas holiday and the New Year’s, would it be safe for individuals who are vaccinated, who are boosted to get together with family in the setting of the home? The answer to that is: Yes. An extra level of protection would be the testing that Dr. Walensky mentioned.
But I want to make sure this is not confused with going to a large gathering — and there are many of these — parties that have 30, 40, 50 people in which you do not know the vaccination status of individuals. Those are the kind of functions — in the context of COVID and particularly in the context of Omicron — that you do not want to go to. "
What's important to understand is that if the group you're intending to join has people attending who can't be verified as to their vaccination status, you should not go there...regardless of the number. If you can be assured that each and every attendee has been fully vaccinated (that's 3 mRNA shots for Adults)..and preferably tested immediately before the event, then you can feel comfortable in going there.
Link: https://www.whitehouse.gov/briefing-room/press-briefings/2021/12/22/press-briefing-by-white-house-covid-19-response-team-and-public-health-officials-75/