At least 175 people have contracted 2019 novel coronavirus (2019-nCoV) aboard a luxury cruise ship quarantined in Japan. The latest total includes 39 newly identified cases among passengers and crew members, plus one case in a Japanese quarantine officer working on the vessel.
The outbreak on the ship Diamond Princess is the largest outside of China, where the virus is thought to have spread to people from animals in a live-animal market in the city of Wuhan, the capital city of the central Hubei Province. The virus’ jump to humans led to an explosion of disease, which, as of yesterday, February 11, the World Health Organization formally dubbed COVID-19, short for “coronavirus disease 2019.”
Since the outbreak began in December, there have been over 45,000 confirmed cases of COVID-19 worldwide and at least 1,115 deaths. But while 2019-nCoV has spread to at least 24 countries beyond China, nearly all of the COVID-19 cases and all but one death have occurred in China.
According to the latest figures from the WHO, 44,730 cases are confirmed in China, while a remaining 444 are outside the country—including the 175 cases linked to the Diamond Princess. The tally is by far the largest outside of the outbreak’s epicenter; the country with the next-largest COVID-19 outbreak is Singapore, with 50 confirmed cases, according to WHO.
Ups and downs
While the daily count of new cases has declined in China—a potential, but certainly not conclusive, sign that the outbreak may be waning—the outbreak on the ship has skyrocketed.
Daily global case counts have gradually declined from a peak of roughly 3,900 on February 4 to roughly 2,000 on February 11. While officials at the WHO said that the outbreak’s trajectory is still unpredictable and that the decline should be interpreted extremely cautiously, the recent decline does feed some hope that the outbreak control efforts in place are working.
Meanwhile, the outbreak on the Diamond Princess—docked and quarantined at Yokohama, south of Tokyo, since February 3—leapt from 10 confirmed cases on February 4 to 175 today. And so far, health officials in Japan have only tested a fraction of the nearly 2,666 guests and 1,045 crew members on board at the time of quarantine.
Screening for COVID-19 on the ship began after a previous guest tested positive for the virus in Hong Kong on February 1. The man, who is from Hong Kong, boarded the Princess January 20 in Yokohama at the start of a 14-day round-trip voyage. The man sailed a leg of the voyage before disembarking during a stop in Hong Kong on January 25. Meanwhile, the ship sailed on. Upon news that the guest tested positive on February 1, the Diamond Princess returned to Yokohama a day early and has been quarantined ever since, with guests in isolation in their cabins.
It is still unclear when and where the man from Hong Kong became infected and how the virus has spread among people on the ship. It may be that the outbreak involved a so-called “super-spreader,” which means that a single infected patient sheds the virus extremely efficiently and infects an inordinate number of people. But again, it is unclear how many people may have brought 2019-nCoV aboard and how—or if—the 175 cases are all linked.
As a report by Reuters noted, roughly 80 percent of the passengers are aged 60 or older, with 215 being in their 80s and nearly a dozen over 90. Those age groups have been among the most vulnerable demographics in the outbreak overall.
Testing began with passengers and crew who had symptoms of COVID-19 and/or had contact with the man who tested positive in Hong Kong. At least 439 of the initial 3,711 people aboard have been tested. Those who have tested positive have been transferred to local hospitals for treatment and isolation. Four of the 175 cases are reportedly serious.
According to local news coverage, the quarantine officer who tested positive was handing out questionnaires and checking the health of passengers and crew members. The officer was following required precautions, wearing a mask and gloves, but was not wearing fully protective gear.
Japan’s health minister, Katsunobu Kato, now wants to test everyone aboard and said that he has the resources to do more than 1,000 tests a day.
The situation for Americans on the ship was addressed in a press conference today with Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases at the US Centers for Disease Control and Prevention. Dr. Messonnier said that the agency was “working closely with the embassy in Japan and the State Department.” Together, they are thinking through what the next best steps are, she said.
Some Americans on board have tested positive, but the number of Americans affected is unclear.