The Centers for Disease Control and Prevention extended a no-sail order for cruise ships late Thursday in a directive that harshly criticized the industry’s handling of coronavirus outbreaks on multiple ships.

Cruise lines voluntarily suspended sailings nearly a month ago for at least 30 days, and have since extended those cancellations into late April or May. The CDC order, signed by director Robert Redfield, says cruising should not resume until covid-19 no longer constitutes a public health emergency, the agency rescinds or modifies the order or for 100 days, whichever comes first. It renews a March 14 mandate.

According to the order, Redfield “finds that cruise ship travel exacerbates the global spread of covid-19, and that the scope of this pandemic is inherently and necessarily a problem that is international and interstate in nature and has not been controlled sufficiently by the cruise ship industry or individual state or local health authorities.”

Marty Cetron, director of CDC’s Division of Global Migration and Quarantine, said the new order was part of a growing recognition of the particular vulnerability of cruise ships to covid outbreaks, given that ships confine large numbers of people to small spaces for long durations of time.

“Everybody has witnessed the tragedy within the tragedy of this pandemic,” he said, referring to what has happened on cruise lines.

He said the U.S. will continue to respond to any medical emergencies or requests for evacuation of critically ill crew members. But the order otherwise calls for a halt of all cruise line activity in U.S. waters, while the industry is required to put forward a new comprehensive plan to detect coronavirus and then mitigate and contain the disease on ships.

The order applies to cruise ships with the capacity to carry 250 or more people, including crew. The agency asks cruise operators to submit a plan within seven days that addresses a host of concerns, including surveillance and reporting of illness on board, crew training, testing procedures, onboard medical care and evacuation logistics.

“An appropriate plan shall be designed to minimize, to the greatest extent possible, any impact on U.S. government operations or the operations of any state or local government, or the U.S. healthcare system,” the order says.

The trade group that represents cruise operators, the Cruise Lines International Association, said in a statement that the industry had already “proactively submitted proposals that are far reaching in prevention, detection, and care – and, importantly, would be led and funded by the industry.”

In a statement, the CDC pointed to at least 10 ships in recent weeks that had reported crew or passengers who tested positive for coronavirus or experienced symptoms; the order notes 15 ships either at anchor or in ports in the United States with known or suspected infection among remaining crew.

Just last weekend, the Coral Princess arrived in Miami with 12 confirmed cases of covid-19 and two passengers who had died on the way to the port. A third died in a hospital. Local medical workers boarded the vessel to help the onboard staff the day after it arrived; a county fire-rescue department delivered oxygen cylinders and brought 12 more passengers to local hospitals. Seven sick crew members were taken to hospitals Thursday, the Miami Herald reported.

According to the CDC, about 100 ships are off U.S. coasts with nearly 80,000 crew on board. The cruise industry’s trade group, Cruise Lines International Association, submitted a plan last week for caring for crew and others on board while ships aren’t sailing with passengers. But that needs to go further, the CDC said, “to reduce industry reliance on government and shoreside hospital resources.”

The agency said that response plan also needs to provide more details on caring for the critically ill, sending additional ships to remove people from infected ships, testing, prevention strategies, disinfection protocols, personal protective equipment and repatriating foreign nationals.

Cetron noted that nearly all passengers have now disembarked, allowing cruise ships at sea better opportunities to isolate and treat any crew members – a generally young and healthy population.

“Now that all passengers are off and we think we’ve responded to all critically ill persons, this is a really good time to take a pause and reevaluate and for the industry to present a really comprehensive…plan for how to contain outbreaks at sea,” he said.

According to the order, any operations such as moving to anchor, discharging waste, disembarking passengers and crew or bringing new crew on board must be done under approval of the U.S. Coast Guard in consultation with the CDC.

In its statement, the cruise industry group said it had been proactive in escalating health and sanitation protocols and transparent about reporting cases “despite numerous challenges beyond the industry’s control.” The group said it was concerned about unintended consequences of the order, which it claimed could lead to 343,000 lost jobs and a $51 billion hit to the U.S. economy if the national emergency were to last for a year.

“While it’s easy to focus on cruising because of its high profile, the fact is cruising is neither the source or cause of the virus or its spread,” the CLIA statement said. “What is different about the cruise industry is our reporting requirements. It would be a false assumption to connect a higher frequency in reporting to increased risk/frequency of infection.”

Cetron, of the CDC, rejected the industry pushback that cruise ships have not played a unique role in spreading coronavirus.

“I think that’s not true,” he said. “This is not to point blame, but we have to be honest about the science and the evidence.”

He said experience from the Diamond Princess and the Grand Princess, where widespread testing of symptomatic and asymptomatic passengers took place after known outbreaks, showed that the “attack rate” of the virus on board was especially high.

“We don’t see those kinds of attack rates in other settings – even in household settings,” he said. “Even in cities experiencing outbreaks, this is pretty dramatic.”

He said cruise ships have not been the only places to struggle but the “unique” characteristics of the tight quarters of a ship, communal eating and entertainment and passenger demographics that skew older can make them especially vulnerable.

“Outbreaks are quite risky in this environment,” he said.

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