@donnyboy, I've participated in a 3 or 4 studies at Rochester Mayo Clinic over the years and really enjoyed helping. The first one back in the mid 80s was a heart study and fairly involved with tests done at St. Mary's Hospital one or more times a week along with a couple of overnight stays all paid for by Mayo. The result for me was a change of my high blood pressure medications due to learning more about the cause of my high blood pressure which was primary aldosteronism. The only really bothersome period for me during that study was a week that I had to wear a blood pressure cuff 24x7 and it took my blood pressure multiple times a day and I had to stop what I was doing at work and stay still.

I also participated in a Flu vaccine study and an RSV vaccine study which only required one trip to clinic downtown for baseline evaluation and instructions for the study and follow up. If I remember correctly both of the studies for the winter season and I had to report to them if I thought I had a case of the flu or was feeling sick so they could make a determination if I need to come in. The study coordinators and the whole team were really helpful. I agree with @colleenyoung that it would be helpful if you make a list of questions and contact one of the coordinators. They will be more than happy to answer any of your questions.