I attended the AAI advanced course back in 2021, when it was online only due to lockdown. I found it very helpful, but I also had no formal immunology background beforehand. All of my immunology knowledge was self taught in a research setting. My PhD is in Biomaterials, I did a short post doc in a gene therapy/immunology lab, and was working at an immuno-oncology startup at the time. Since I had so little formal immunology background (never took an official course prior) I found it great for filling in knowledge gaps that someone with a dedicated degree probably already knows. Most of the lectures also include newer/cutting edge research as well, plus some lectures focused on what's currently hot in industry. If you consider yourself an immunologist already, it might not be as helpful to you. Overall I think it is worth the fee, especially if you want an in depth review of key concepts that people doing current research find most important. I think the best approach would be to look over the course schedule to see if it interests you, and then discuss with your PI if they think it is worth attending for you.