More than 1,350 Covid cases reported by cruise ships in United States since June, CDC reveals

Despite cruise lines' efforts to impose strict public health rules, Covid-19 has still found a way on board.

According to the CDC data, cruise operators confirmed 1,359 cases between June 26 and October 21, a roughly four-month period that represents a rebound for the industry.

Many of those involved breakthrough infections of people who were fully vaccinated. During that time, operators reported 49 hospitalisations and 38 medical evacuations for Covid-19 or Covid-like illnesses.

At least one person died after testing positive during a cruise.

As the US government allowed cruises to resume with some restrictions, ships added vaccine requirements, testing rules, capacity limits and mask mandates.

Cruise lines have acknowledged positive cases over the past few months, but the full scope was not previously known. The CDC included the numbers in its extension of a "conditional sail order" that outlines operating rules for cruise lines during the pandemic; that order will shift from mandatory to voluntary on January 15.

In making the case to extend the order beyond a November. 1 expiration date, CDC director Rochelle Walensky wrote that "despite the best efforts of cruise ship operators to provide a safer and healthier environment for crew and passengers," outbreaks had continued.

The document provides several examples, mostly involving breakthrough cases, including one in which a symptomatic passenger who tested positive on a ship in late July was linked to 20 more confirmed cases over two sailings.

In that case, 18 service workers and two passengers were infected. One ship reported 58 positive cases between July 24 and August 28, and another reported 105 confirmed cases on four back-to-back trips between August 19 and September 7.

One reported 112 cases on four voyages between August 21 and September 7.

In each of those cases, the ships reported between 96.4pc to 100pc of people aboard were vaccinated.

Aimee Treffiletti, a captain in the US Public Health Service and lead for the CDC's maritime unit, told The Washington Post in an interview last week that vaccinations should continue to be "an essential part" of cruise line health plans even after the rules expire.

"That's one of the main reasons we haven't seen medical systems overwhelmed on board, because we have such high vaccination rates on board," she said.

The CDC does not identify specific ships or companies in its order, but the public health agency does maintain a website showing whether there have been recent cases of Covid-19 on ships sailing in US waters.

In an email, Cruise Lines International Association spokeswoman Bari Golin-Blaugrund said the trade group estimates that about 600,000 customers sailed aboard ocean ships during the four months since the industry resumed in the United States.

"The relatively low occurrence of Covid-19 during that period, particularly when compared to the rest of the country, further shows the leadership of the cruise industry and the effectiveness of the science-backed protocols that have enabled a successful return to operations around the world," she wrote.