By Hannah Sampson
When two passengers on a Celebrity Cruises ship tested positive for the Coronavirus during the company's first Caribbean cruise this month, it was an unwelcome development. But not entirely unexpected.
The CEO of Celebrity's parent company, Royal Caribbean Group, had predicted months earlier that the virus could sneak on board, despite precautions to keep it off.
"We've been very explicit about this: You can't eliminate Covid-19 in society, and you can't totally eliminate it on a cruise ship," chief executive Richard Fain said at the Phocuswright Conference in November. "The objective is not to say there can't ever be a case on board. But if there's a case, it is isolated out and it remains a case, rather than an outbreak."
As cruise ships slowly start to return to service in the US - months after restarting in limited fashion in places, including Europe and Asia - all eyes will be on the seas to see whether the embattled industry can avoid the kind of early outbreaks that laid it up for more than a year.
Their return is buoyed by expert advice, cruise-specific health guidelines that took months to develop, plenty of new research on how the virus spreads, advances in rapid testing and - most importantly - the availability of highly effective vaccines.
Most of that was not available to cruise lines in the earliest days of the pandemic, when the virus tore through ships and passengers and crew fell ill as they were forced to remain on board. Operators scrambled to arrange plans to get sick passengers to facilities on land - though some who were sick died before they could leave the ship.
More than a year later, recent examples have shown the virus isn't done with cruise ships yet. Just days before the Celebrity case in the Caribbean, two passengers on an MSC Cruises ship in the Mediterranean tested positive during routine mid-trip screening.
And earlier this month, one of the first voyages scheduled from the US was postponed for nearly a month after eight crew members tested positive. They had received the one-dose Johnson & Johnson vaccine, but not enough time had passed for them to be fully vaccinated when they tested positive.
"You can never entirely eliminate Covid from any community, even a fully vaccinated one, but you can keep people safe," said Vin Gupta, a pulmonary/critical-care physician who teaches health metrics sciences at the University of Washington's Institute for Health Metrics and Evaluation. He said that if passengers were not vaccinated, he would recommend mandatory rapid PCR tests every 48 hours, and masking.
The industry is still focused on keeping sick passengers on the ground through testing requirements, health screenings and vaccine mandates or recommendations. But operators have also introduced a number of measures to keep the virus from spreading if someone is found to be infected.
While exact protocols vary depending on the cruise line, the lines are using a variety of measures to avoid outbreaks, according to Cruise Lines International Association spokeswoman Bari Golin-Blaugrund.
Those include testing passengers and crew on the ship and isolating positive cases quickly in dedicated staterooms, as well is identifying, screening and quarantining anyone who was a close contact of infected passengers or crew.
Ships have updated their medical facilities and staffing to better be able to handle Covid-19 cases if they emerge. And operators have prearranged agreements with destinations to bring patients to land and provide them with care, a place to stay and transportation.
Positive cases have to be reported immediately to authorities. And ships have disinfection procedures in place after someone tests positive.
Ships are also sailing at reduced capacity to allow for social distancing on board, and masks are required in many cases, depending on the vaccination status of passengers.
As requirements by the Centres for Disease Control and Prevention are updated and pandemic conditions change, cruise protocols change, too, making it difficult for passengers to know in advance exactly what their trip will be like, or what they could expect if they or someone on their trip tested positive.
"The best I think that can happen is to basically have a fully vaccinated ship," said Clare Rock, an infectious disease physician and associate professor of medicine at Johns Hopkins School of Medicine. She has been providing expert advice to Carnival Corporation.
"When we have these large groups of fully vaccinated people together, the risks of someone actually getting sick or ill from Covid is really, really, really minuscule. Because when you have a group of close to fully protected people like that together, there's not really significant virus to transmit from person to person," Rock said.