The cruise ship Diamond Princess, quarantined in Yokohama for the next couple of weeks, has about 3,700 people on board. The vessel looks impressive but those confined to inside cabins must feel as if they are not just doing time but have been sentenced to death. Everyone knows how unhealthy cruise ships can be. Forty new cases of novel Coronavirus were declared today, tripling the number of infected.

The World Dream, a cruise ship in Hong Kong with a similar complement of human cargo, has so far had no positive test results. In New Jersey, a small number of passengers on the Anthem of the Seas has been screened and four taken to hospital for further tests.

Whether you consider Diamond Princess a modern prison hulk or a giant petri dish, it is perfect for modelling.

I have logged patient zero’s appearance on 20 January, though he had left the vessel just before that date in apparent good health. The incubation period for this coronavirus is 5 to 14 days, with 6 or 7 days seeming to be commonly accepted now. I have plumped for 7 days. To arrive at a Total Infected figure approximating 61 today, and no fatalities, I have had to set an R₀ of 3.9 and a low mortality rate of 1%. In three days from now, this model predicts 75 passengers/crew infected and three deaths.

The good news is – the virus will burn out in just over a month. The bad – 404 people may have died by then.

There haven’t been any fatalities yet from the Princess but if the reality matches this projection it may validate the tool and make my country projections seem more believable. (I really can’t imagine 10 million UK citizens succumbing to the virus before mid-summer.)

A new country has been added to the list on the Johns Hopkins map – called “Others”, it currently comprises just the Diamond Princess. It is the hardest hit “country” of the 28 outside Mainland China.

Model: Andology Novel Coronavirus Prediction Tool.