Quarantine the passengers, and the crew keeps serving them dinner

On 5 February 2020, passengers on a cruise ship at Yokohama were asked to
observe a 14-day quarantine in their cabins. About 3,700 people were on
board and the quarantine ran nearly four weeks; by the end, **roughly 700
laboratory-confirmed cases of COVID-19.**

The quarantine had a hole in it that was structural rather than accidental.

**After quarantine began, crew members continued to perform their regular
duties, delivered meals to passengers, and remained in their cabins when
they were not working.**

A cabin quarantine for 2,600 passengers requires about 1,068 crew to keep
moving through the ship, three times a day.

Where the cases were

Of the 20 crew cases confirmed by 9 February:

Deck 3 is where the food service workers lived. More than **80% of crew
cabins were on decks 2–4**, while passengers were on decks 5–12 — so the
crew's outbreak had its own geography, in a part of the ship passengers never
saw.

**The crew dining area was identified as the primary area of congregation for
the crew; passengers did not have access to it.** The place that concentrated
the crew's exposure was the one place the quarantine did not reach, because it
was not a passenger space.

The order it happened in

The first two identified cases were passengers, with symptoms beginning
22 and 23 January — one of whom had already disembarked on 25 January,
before the ship reached Yokohama. **The index patient could not be
determined.**

Because those dates come first, **COVID-19 was likely transmitted from
passengers to crew and then spread among the crew, especially among food
service workers.** The first crew case was **a food service worker with fever
on 2 February.**

And the quarantine started too late to be a clean boundary: **seven ill crew
had symptom onset within three days of quarantine beginning**, and **three of
the 20 had close contact with another confirmed crew member before quarantine
was implemented.** Some transmission had already happened.

What the ship shows

Quarantine is a spatial idea — keep people apart — and a ship makes visible
what is true of any quarantine that depends on people delivering things: **it
is only as good as its exceptions.** The passengers were separated from each
other. The crew were separated from nobody, ate together, and lived one deck
apart from the outbreak among themselves.

Source: Centers for Disease Control and Prevention, MMWR.