The woman at Harvard didn't tell my how many applicants, but there are usually ~8 spots and limited department funding (according to a professor that I've been working with in that department). Not sure if they're interviewing, I think it just depends on the application and if they have any questions to ask you.
Congrats on Hopkins, I think my application was held up because of a transcript coming in from China... hopefully I hear from them soon! The waiting is the worst...
Cheers,
B