Data were analyzed to identify higher-risk work spaces. Those working in tighter spaces (e.g., reactor, engineering, supply, and weapons departments) appeared more likely to have confirmed or suspected Covid-19 than those working in a combination of open-air and confined conditions (e.g., air and deck crew). Members of the medical department, who wore personal protective equipment when evaluating crew members, had a somewhat lower attack rate (16.7% [8 cases among 48 personnel) than the overall crew, despite being at highest risk as a result of exposure to patients with Covid-19 in a small space.