As I recall, there were no supplemental essays on the Harvard secondary last year, except if you were going for the HST program. In that case, you had to write a one-page essay describing how research has influenced your education and how you plan to use it to shape your medical education. Or something like that.
Yeah, I don't remember any essays as well. Just had to restate your extracurriculars, and answer some of the basic questions (ever convicted of a felony, ever suspended, etc.). If you have been out of school, it might ask you what you have been doing in the interim, but I'm not sure about that.