I went on HM in April and got COVID while onboard. Initially I thought it was allergies acting up since I had been away from our pets for a week and a half. But a day or two later I woke up with a very slight sinus headache. I decided to take some sinus medication and while I laid in bed waiting for it to kick in, I read posts on our sailing's FB group. People were posting left and right about testing positive.
I would not do anything differently. The vax/boost did it's job. The worst part of the illness was the quarantine. I luckily had no symptoms aside from the initial sinus headache save for a slight cough for a 2 or 3 days.
We are already planning our next cruise.