Sadly, we never learn the full contents of the letters that Lara Jean writes to her crushes in the movie. In the book, when Peter approaches Lara about his letter, he tells her he doesn't have a sexually transmitted infection. We're guessing that doesn't make it into movie Peter's letter, since he only mentions that Lara thinks he has golden specks in his eyes and any question of an STD would be too major not to point out.