Not sure if this is relevant to your study, but having already cancelled two Covid second vaccination appointments to avoid short notice working days at the behest of the company I was then told to cancel the third one because they wanted me to fly the day after. I ‘had words’ because I felt that my personal health was being put at risk to suit them. I was then accused of refusing to fly! I certainly wasn’t and put them straight in writing.
I eventually managed to get the vaccination done just inside the recommended three month period.