. . has delayed a cruise because 8 of the crew tested positive even though they had been vaccinated. It was noted that these crew members tested positive after vaccination but before the time span it takes for the vaccination becomes fully effective.

It has also been noted that those crew members testing positive after vaccination had very light symptoms or were asymptomatic. I have no info on the others, but the J&J (which I got) is noted for mild symptoms in cases where a vaccinated person contracted COVID.

Persons with compromised immune systems are most likely to become seriously infected even though vaccinated, because their immune systems are not up to the task of producing full immunity.