I'm curious about biological sciences invitations as well. My application status has been "awaiting consideration by department" for the past 2 months, then suddenly on Thursday it changed to "under consideration by department." This makes me a little skeptical that they even processed my Gates-Cambridge application to begin with, if it's true that it is only being looked at now. I didn't have any outstanding forms or anything, and submitted everything well before the October 12 deadline. I do have a dual citizenship and I'm wondering if for some reason I have been filed as an international applicant instead of a US one for Gates, but my entire work and educational history should make my US primary citizenship clear, and I'm pretty sure I had to indicate a "primary" and "secondary" citizenship on the Cambridge app.
Of course I could easily just not have received an interview, which statistically is much more plausible anyway! I'd love to know if any biologists have received interview invitations thus far.