Okay, I can’t let this go since I am in the “old f**t” category. 它 seems to me that cruise lines should have been requiring a doctor’s permission slip for 65+ years of age passengers for the last few decades. Look at the CDC stats for the common flu at //www.cdc.gov/flu/about/burden/2017-2018.htm . Oh, remember there is a vaccine and treatment for the seasonal flu.
Also, the lines should require that all passengers have their flu/pneumonia shots before boarding since they are more deadly than Covid-19. See the chart at: //www.cdc.gov/nchs/nvss/vsrr/covid19/index.htm