Two passengers aboard the quarantined Princess Cruises ship that's docked in Japan told CNBC on Wednesday that containment measures to prevent the new coronavirus from spreading have failed.

"[Japanese government officials] are letting some people who they claim are the most elderly and vulnerable off the ship," said Gay Courter, who's being held on the Diamond Princess with her husband, Phil. "But they do it behind plastic wrap and fire engines so the press can't see. It is proof that this whole thing has failed."

The Carnival-owned company last week placed 3,700 passengers and crew under a two-week mandatory quarantine after 10 passengers tested positive for the fast-spreading virus. It's a move required by the Japanese Ministry of Health. Since then, a total of 175 people, including a quarantine officer, were confirmed to have the virus.

"Those numbers that we hear from the captain over the loud speaker are terrifying, especially with that exponential curve going up just like in China," Gay Courter said on "Squawk Box."

China's National Health Commission said Wednesday that there were 2,015 confirmed new cases on the mainland and 97 additional deaths related to the new, deadly strain of coronavirus, most of them occurring in Hubei province. The Chinese government said overnight that a total of 44,653 cases have been confirmed and 1,113 people have died in the country.

She said many passengers aboard the ship, including her husband and herself, haven't been tested for the deadly virus outside of initial temperature taking.

"We take our temperature once a day, voluntarily," Phil Courter said. "We are supposed to call if our temperature goes higher than the standard they've set. But that's voluntary, there's nobody checking on anybody."

"Frankly, it's terrifying," he added.

A spokesperson for Princess Cruises was not immediately available for comment.

The World Health Organization said there's been more than 150 coronavirus cases in about two dozen countries outside of China and declared the virus a global health emergency.

Officials on the ship have arranged for short periods of time that passengers can go on the ship's deck to get fresh air and exercise, though Phil Courter said the pair haven't "taken advantage of that" since they have a balcony in their room.

The ship is expected to remain under quarantine until Feb. 19, though the Courters believe they'll be held longer.