I've heard MIT calls accepted students in the past and doesn't give acceptances out through email! Best of luck to all those still waiting to hear back!
Caltech interviewed 27 inorganic applicants in the first round (10 min interviews). They invited 18 back for a 4 minute Zoom call Thursday. It was not specified as a second interview, just a follow-up from the original interview.
Hope this helps! Nervous af for Thursday. Anyone else invited back?