Abstract

Objective: Cruise line operations were suspended in U.S. waters due to the COVID-19 pandemic. We describe demographic characteristics, time since completion of a primary series of COVID-19 vaccine and working conditions of crew members testing positive for SARS-CoV-2 following resumption of passenger operations in the United States during a period of Delta variant predominance.

Methods: Ships sailing under CDC’s Framework for Conditional Sailing Order reported SARS-CoV-2 test results, vaccination rates, and hospitalizations/medical evacuations due to SARS-CoV-2 infection to CDC daily. Ships experiencing large outbreaks (≥20 SARS-CoV-2–positive cases among crew/passengers within 14-days) submitted additional case data.

Results: During June-October 2021, 1,079 SARS-CoV-2-positive crew members were reported to CDC; 402 cases from large outbreaks had case-level data and were included in this analysis. All crew members completed a primary series of COVID-19 vaccine before they were infected. Median number of days from completion of a primary series of COVID-19 vaccine to infection was 76 days (interquartile range [IQR]:53–98). Most crew received the Janssen vaccine (n=302; 76%), and Janssen vaccine recipients had lower median number of days from last vaccination to infection than recipients of vaccines from other manufacturers [75 days (IQR: 55–87) vs. 86 days (IQR: 46–125; p=0.03)]. No hospitalizations or medical evacuations for SARS-CoV-2 were reported; 263 infected crew (65%) were asymptomatic at time of testing. Forty percent of infected crew shared either a cabin or restroom with another crew member at time of diagnosis.

Conclusion: We analyzed cases of SARS-CoV-2 infections during the Delta-predominant period among crew members associated with large outbreaks on passenger-voyaging ships. Severe illness was rare and most crew was asymptomatic; however sharing closed spaces with other crew members might increase the risk of exposure to SARS-CoV-2. Enhancements to existing COVID-19 mitigation measures and facilitating booster vaccination might reduce the risk of infections and severe illness in such congregate settings.