I think the one after us is the one you are referring to. There where several cases on the sailing we took but it would have been a nightmare to catch them all. People got on the ship in 2 ports (Martinique and Guadalupe) as well as got off as that was their final destination. The only testing done at any port or to reboard the ship was a temperature sensor pointed at you. These were early days when no one knew what was coming.My wife and I took the new years cruise from La Romans with the costa line. Either the cruise you took or the next one ended up with 50 infected doctors from Santiago, several of which died from covid. This was before the vaccines arrived.
Hopefully with everyone (guests and staff) showing proof of vaccination these situations will be a thing of the past or on a much smaller scale.