Abstract

Objective: Following suspension of cruising due to the COVID-19 pandemic, passenger voyaging operations resumed in June 2021 when cruise lines, with assistance from the Centers for Disease Control and Prevention (CDC), implemented protocols to manage COVID-19. We describe demographic characteristics, time since vaccination and living and working conditions of crew members testing positive for SARS-CoV-2 following resumption of passenger operations in the US 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 (e.g. demographics, vaccination history, living/working quarters and numbers of crew members who were close contacts of cases).

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 cases completed a primary vaccine series before they were infected. Median number of days from last vaccination to infection was 76 days (Interquartile Range (IQR): 53-98). Most crew received the Janssen vaccine (n=302; 76%) and Janssen 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 cases (65%) were asymptomatic at time of testing. Forty percent of cases shared either a cabin or restroom with another crew member at time of diagnosis.

Conclusion: SARS-CoV-2 infections were reported among vaccinated crew member’s onboard passenger voyaging ships although severe illness was rare. Enhancements to existing COVID-19 mitigation measures and facilitating booster vaccination, ensuring vaccinations are up to date, may reduce the risk of infections in such congregate settings.

Keywords: COVID-19; CDC; Vaccination; Janssen vaccine; Medical evacuations