Symphony of the Seas departed on December 11 with 6091 guests, 95% of whom were fully vaccinated.
In a statement, RCI said that all crew were fully vaccinated against COVID and tested weekly.
To sail on Symphony OTS, passengers over age 12 must be fully vaccinated against COVID and test negative prior to boarding.
Kids not yet vaccinated have to provide a negative PCR test before sailing and also test negative at the cruise terminal before boarding.
Of the 48 positive cases, a total of 98% were fully vaccinated. The positive individuals were identified as a result of contact tracing after a passenger tested positive.
According to a statement from RCI, each person had quickly gone into quarantine.
"Everyone who tested positive was asymptomatic or had mild symptoms, and we continuously monitored their health."
6 passengers were disembarked earlier in the voyage and transported back home. The additional travelers received assistance upon the arrival of the ship on Saturday.
Future itineraries for the ship have not been impacted.
The 7-day "Eastern Caribbean with Perfect Day Cruise" departed PortMiami on December 11. Feature ports of call included Philipsburg, St Maarten Island, Dutch Antilles (December 11), Saint Thomas USVI (December 15), and Coco Cay, Bahamas, Royal Caribbean (December 17).
For more Symphony of the Seas incidents and accidents see the ship's CruiseMinus page.