Despite a 100% vaccination rate on the vessel, there was still an outbreak of COVID, suggesting that vaccine effectiveness is severely waning. 

“Despite every cruise line requiring passengers and crew to be fully vaccinated before boarding, a cruise ship returning from a sail across the Gulf of Mexico and the Caribbean Sea with thousands of passengers onboard detected an outbreak of COVID-19 – the cruise line detected ten COVID infections among its guest and crew. Those who were infected were fully vaccinated and were forced into quarantine. ”

https://www.zerohedge.com/covid-19/covid-outbreak-us-cruise-ship-despite-fully-vaxxed-passengers