The CDC said 20 cruise ships at port or anchorage in the US have known or suspected Covid-19 infection among the crew. Credit: Cruising Times.

It’s time to drop anchor, says the Centers for Disease Control and Prevention (CDC) in Atlanta.

While some cruise ships with Covid-19 patients are still looking for ports, the CDC is extending its no-sail order for 100 days or until the pandemic is deemed over, Theresa Norton of Travel Pulse reported.

“We are working with the cruise line industry to address the health and safety of crew at sea as well as communities surrounding US cruise ship points of entry,” said CDC Director Robert Redfield.

The order will remain in place until one of three situations occurs: The Secretary of Health and Human Services’ declares the Covid-19 public health emergency is over; the CDC director rescinds or modifies the order; or 100 days from the date of publication in the Federal Register, the report said.

Cruise lines halted operations voluntarily on March 14 and many companies have extended their suspensions, the report said.

In announcing the no-sail order, the CDC said in a statement that “cruise ship travel markedly increases the risk and impact of the Covid-19 outbreak within the United States.”

In recent weeks, at least 10 cruise ships reported crew or passengers that tested positive or experienced respiratory symptoms or influenza-like illness, the report said.

Currently, the CDC said, there are approximately 100 cruise ships remaining at sea off the east, west and Gulf coasts, with nearly 80,000 crew onboard.

Additionally, the CDC said 20 cruise ships at port or anchorage in the US have known or suspected Covid-19 infection among the crew who remain on board, the report said.

The CDC, the US Coast Guard, and the Department of Homeland Security have been working with the cruise industry on a framework to combat Covid-19 on ships with international crew members who remain on board and at sea.

The order requires that cruise lines develop a detailed operational plan approved by CDC and the US Coast Guard to address the Covid-19 pandemic, including a response plan with limited reliance on state, local, and federal government support, the report said.

Small ships with fewer than 250 passengers and crew are not affected by the CDC’s ruling, CruiseCritic reported.

This allows small-ship lines like Alaska Dream Cruises, American Cruise Lines, Blount, Lindblad Expeditions and UnCruise Adventures to resume operations of their entire fleets before the expiration of the ruling.

Ironically, information gleaned from cruise ship outbreaks is helpful for people making decisions on how to manage the epidemic, reported.

“Cruise ships are like an ideal experiment of a closed population. You know exactly who is there and at risk and you can measure everyone,” says John Ioannidis, an epidemiologist at Stanford University in California.

This is very different from trying to study the spread in a wider population, where only some people, typically those with severe symptoms, are tested and monitored.

Using the Diamond Princess data from Japan, a team reports in Eurosurveillance that by 20 February, 18% of all infected people on the ship had no symptoms.

“That is a substantial number,” says co-author Gerardo Chowell, a mathematical epidemiologist at Georgia State University in Atlanta.