I interviewed recently, and my interviewer was a retired doc that had been on the adcom for 20 years. He actually talked way more than me, which I wonder about, but the upside is he told me the whole admissions process at HMS. I'm not sure if this would help anyone, but if you're curious:
So your initial app gets screened by six individual screeners. Then you get an interview. You have two interviewers, who type up a review of the interview, and this gets added to your file. Your interviewers don't actually speak for you, I don't think. Then a third person gets handed your file, along with the interview reviews. They read your file and become your advocate to the executive committee.
Immediately after the interview, half the interviewees are cut. 800 down to 400 or something. If you make the 400, at the end of the season the executive committee will cut it down again to 200 by voting, and these are the offers. I guess this explains why it's not rolling, although it seems they could send rejection notices after the first cut.
There's also subcommittees, which seem to be organized by school/location. I'm from the west coast, and my interviewer straight up told me he was on the west coast subcommittee, meaning he saw a lot of applicants from my undergrad, as well as the neighboring undergrads. He was familiar with my school's curriculum and premed advising program. I'm not sure if this particular subcomittee also votes on me.
I'm sorry if I remembered this wrong or misunderstood what he said.