Yesterday, the Centers for Disease Control and Protection (CDC) updated its color-coded list of ships that tracks where passengers or crew have tested positive for Covid-19. The list is updated multiple times a week.

The agency currently identifies 86 ships where the number of Covid-19 cases meets the threshold for investigation — a 178% jump in 10 days — as the omicron variant spreads quickly across the U.S.

Forbes reports that the 86 ships are on yellow status, which signifies that the number of reported Covid-19 cases exceeds .10% — or one-tenth of one percent — of the total number of people onboard the ship.

“CDC has been collaborating with global public health and industry partners to learn about omicron, as we continue to monitor its course,” wrote Jasmine Reed, a CDC spokesperson, via email. “We are still learning how easily it spreads, the severity of illness it causes, and how well available vaccines and medications work against it.” 

Among the 86 cruises in yellow status under investigation, Carnival operates 32, Walt Disney operates four, Royal Caribbean operates 25 and Norwegian Cruise Line Holdings operates 16.

In a report published in late October, before the omicron variant was identified, the CDC noted that cruise lines logged 1,359 Covid-19 confirmed cases between June 26 and October 21 of this year. While most of these cases were asymptomatic or mildly symptomatic, 87 of those who tested positive needed to be hospitalized or medevaced off the ship.

“CDC acknowledges that it is not possible for cruising to be a zero-risk activity,” Reed said. “The chance of getting COVID-19 on cruise ships is high because the virus spreads easily between people in close quarters aboard ships.”