I applied MD/MPH too but designated it from the beginning. About a month after I was complete, I got an email from the School of Public Health asking me to say which of four public health tracks I was interested in, and to respond within five days. But it didn't seem to have any information re: a decision made on my application, the email looked like it was information they wanted from all MD/MPH applicants. I know this isn't much, but it's the only communication I've heard from the School of Public Health so far. Hope this helps!
Also, congrats on your acceptance! You could always try calling admissions at the School of Public Health too.