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Why health experts advise cancelling cruises amid coronavirus

Experts warn that cruise liners pose special danger as the coronavirus crisis worsens, and call on the industry to rethink ship design.

Close quarters, poor hygiene, passenger mix can create an onboard Petri dish

The Grand Princess cruise ship, carrying passengers who have tested positive for coronavirus, passes underneath the Golden Gate bridge in San Francisco, on Monday. (Kate Munsch/Reuters)

The coronavirus outbreak on the cruise ship Diamond Princess started with a single passenger who came aboard in late January with a slight cough, and then developed a fever shortly after disembarking, six days later. 

By the time doctors in Japan started testing the remaining passengers and crew on Feb. 3, there were 10 cases. After a 14-day quarantine, that number ballooned to 619, with seven resulting deaths so far.  

A new study modelling the onboard outbreak, published in the Journal of Travel Medicine, reaches some sobering conclusions about how much worse — or better — things might have gone.

In the early stages of the shipboard epidemic, the rate of infection on the Diamond Princess was four times higher than in Wuhan, China, the epicentre of what has now become a global outbreak. Left unchecked, the disease would have eventually touched 79 per cent of those on board, some 2,900 people, the Swedish researchers calculate. 

However, if all passengers and crew had been relocated, assessed and, where necessary, isolated when the first 10 cases were discovered, the outbreak might have been limited to a total of 76 people, they say. 

The difference was the boat. "The cruise ship conditions clearly amplified an already highly transmissible disease," the epidemiologists write. 

Floating Petri dishes

Doctors have long known that it doesn't take much to turn a pleasure cruise into a ship of sickness. Passengers and crew are regularly laid-low by influenza, food poisoning or gastrointestinal viruses like Norwalk. Over the past decade, cruise companies operating out of U.S. ports alone have reported an average of almost 3,200 such illnesses each year. 

But the coronavirus outbreaks aboard the Diamond Princess — and now its Carnival Cruises sister ship, the Grand Princess, where 21 people and counting have been diagnosed with COVID-19 — show how the close quarters of onboard life have become potentially life-threatening. The current generation of massive, floating luxury hotels — some of them ferrying more than 6,000 passengers, from all over the world, each voyage — can function like a Petri dish, creating the perfect environment for the spread of a plague.

"Cruise ships really provide a fairly unique situation because you take a large group of people and you confine them to a rather limited space, and really you rely on excellent hand hygiene and infection-control measures to be in place to prevent infections from spreading very widely," said Dr. Abdu Sharkawy, an infectious disease specialist with the University Health Network and associate professor at the University of Toronto. 

Unlike airplanes, where a majority of passengers tend to originate from one region or country, cruise ships host travellers from all corners of the world. And while plane passengers share a confined space for a few hours, people aboard ships are in close quarters for days, if not weeks.

On Monday, Canada's Chief Public Health Officer Dr. Theresa Tam, asked Canadians to "think twice about being on cruise ships." The U.S. Centers for Disease Control has similarly recommended that all travellers — and most particularly those with underlying health issues — "defer" cruise vacations for the foreseeable future. 

Sharkawy says, as March break approaches, vacationers need to "use common sense" and look at what has already happened on the high seas. 

"If I had a cruise booked, I would frankly cancel it," he said. "You just don't have that degree of control, you don't have that amount of flexibility when you're stuck on a vessel with 3,000, or 4,000, or more, other passengers and you're kind at the mercy of the local authorities."

Ross Klein, a sociologist at Memorial University in St. John's, has been studying the cruise industry for more than two decades, tracking outbreaks and other on-board problems. He says the cruise companies have developed a fairly workable strategy to deal with things like stomach bugs and the flu, with illnesses hitting just a tiny fraction of the 30 million passengers they carried globally in 2019. But that playbook clearly isn't working for COVID-19.

"I think the coronavirus caught them by surprise and I think they just weren't sure what to do," says Klein. "It's almost like being caught like deer in the headlights."

Klein says that part of the problem might be that a modest amount of sickness has traditionally been a money-maker for cruise companies. "There's a revenue stream that comes from illness, not just the cost stream," he explains. On-board health care isn't free. "U.S. physician prices, you know? I mean, $150 for an office visit. And if you need drugs, you've got to pay too … The doctor gets a commission, and the ship makes money, and everybody's happy. Except for the passenger who doesn't have insurance."

Over the weekend, the Cruise Lines International Association (CLIA), an industry body, unveiled a coronavirus action plan, which will deny boarding to people who have visited or travelled from South Korea, Iran or China, or anyone who has come in contact with a COVID-19 patient within the past 14 days. All passengers will also have their temperatures taken as they embark, with those showing a fever above 38 C referred for secondary screening. 

CBC's Jonathan Gatehouse talks about how cruise ships are like petri dishes for disease spread. 3:57

Whether such measures will be sufficient to protect cruise passengers, who tend to skew older — one-third of all who sail are aged 60 or above, the age group most at risk from COVID-19 — remains to be seen. 

The CLIA did not respond to a request for an interview. And the three major ocean cruise companies — Carnival, Royal Caribbean and Norwegian — all declined to provide CBC News on-board access to document their cleaning and coronavirus control measures. 

Radical redesign

Some experts say the coronavirus crisis points to a need to reimagine the spaces where we work, play and travel, and to start adapting them for 21st century, global health challenges.

"We have to think beyond the everyday experiences. We have to anticipate risks and respond to threats," said Lindsay Tan, who studies how pathogens and people intersect as director of the Design Ecology Lab at Auburn University in Alabama. "So that's both the shape of spaces, how big they are, how many people are going to be in them, how they're going to be used, but also the materials that we're using. Different materials have different properties that carry different loads of virus; properties that are easier to clean."

For cruise companies that may mean challenging consumers' definition of "high-end" and moving from fabric finishes to surfaces that can be more easily cleaned. 

"If I told you that your cruise ship was going to have a vinyl headboard you might not think that sounds really luxurious, but I assure you there are properties that we can put into vinyl now that allow it to be comfortable, luxurious and safe," says Tan. "We're already doing it in health-care spaces. You can have a seat that is beautiful and comfortable, and it's also able to be washed down with bleach." 

The cruise industry is trying its best to weather the storm, by waiving cancellation fees and penalties, and offering full credit for passengers who agree to rebook for future voyages. 

Klein predicts that major PR campaigns and deep discounts will soon follow, in an effort to quell public fears.

That's what has worked with past outbreaks of lesser illnesses. But with lives on the line, convincing people that it is safe to sail, might be a much tougher sell.

"It could be years and years before people have confidence," said Klein.

About the Author

Jonathon Gatehouse

CBC Investigative Journalist

Jonathon Gatehouse has covered news and politics at home and abroad, reporting from dozens of countries. He has also written extensively about sports, covering seven Olympic Games and authoring a best-selling book on the business of pro-hockey. He works for the national investigative unit in Toronto.

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