Corrections & clarifications: The Centers for Disease Control and Prevention found that novel coronavirus RNA, or genetic material, not the coronavirus itself, was identified on surfaces in Diamond Princess cruise ship cabins up to 17 days after cabins were vacated.

A new Centers for Disease Control and Prevention report into the spread of the novel coronavirus on cruise ships looked into the rapid spread of the disease on the ships and beyond individual voyages.

The CDC noted there was coronavirus RNA, or genetic material, found on surfaces in the cabins of both symptomatic and asymptomatic infected passengers on the Diamond Princess cruise ship – 17 days after passengers had left the cabins. Of note, the cabins had yet to be disinfected.

While the data doesn't show if transmission of the virus occurred from surfaces, the CDC report recommends exploring that further.

"Just as mosquitoes spread malaria and ticks spread lime disease, cruise ships have been spreading coronavirus," former CDC director Dr. Tom Frieden told the USA TODAY editorial board and reporters on Tuesday when asked about the report.

The report outlines the responses on board several high-profile cruise ships, including the Diamond Princess and Grand Princess. Between the ships, there were more than 800 COVID-19 cases that led to 10 deaths.

"Not mentioned in the report is the fact that Princess Cruises volunteered to preserve select staterooms onboard Diamond Princess, known to have been occupied by positive cases," Princess Cruises said in a statement to the trade publication Cruise Industry News. "This testing was done in full collaboration with the Japan Ministry of Health and U.S. CDC.

It continued, "According to researchers with Japan’s National Institute of Infectious Diseases, what was detected on surfaces was SARS-CoV-2 RNA*, NOT live virus, in select cruise ship cabins after they were vacated, and this testing was intentionally conducted before disinfection occurred. These findings were expected because Princess Cruises voluntarily preserved these staterooms for this testing."

The CDC found that Diamond Princess passengers transmitted the disease before quarantine and crew infections peaked after the quarantine was implemented. And 17.9% of those identified as infected never developed symptoms, which the CDC said could partially explain the high infection rate among the ship's passengers and crew.

As for the Grand Princess: Crew members likely got infected on the ship's first voyage (Feb. 11 to 21, which sailed round-trip from San Francisco) then transmitted the disease to passengers on the second. The second trip, when the Grand Princess departed San Francisco on Feb. 21, included most of the ship's 1,111 crew and 68 passengers from the initial voyage.

Between Feb. 3 and March 13, the U.S. confirmed about 200 cases of COVID-19 from returned cruise travelers. At least 15 states have reported cases associated with cruise travel to the CDC.

Major cruise lines paused sailing operations to and from U.S. ports (and around the world) amid the ongoing crisis earlier this month.

Could this have gotten done sooner? "There was concern for the economic impact on the cruise industry that prevented that from being done," Frieden said. "There aren’t always conflicts between public health and economics but here there really was one," he added.

Princess Cruises had a health problem long before back-to-back outbreaks of the new coronavirus on the Diamond and Grand Princess ships.

Their passengers fell sick extraordinarily often. Nearly 5,000 people onboard Princess ships in the past decade have suffered from bouts of vomiting, diarrhea – or both – in numbers widespread enough that government health officials issued alerts on 26 outbreaks.

Yet Princess, with 18 ships in the world's largest cruise company, Carnival Corp., consistently earned high marks on U.S. inspections that were supposed to protect 30 million people taking cruise vacations each year.

A USA TODAY investigation found the high-profile scoring of inspections administered by the Centers for Disease Control and Prevention masks how frequently ships are cited for health and sanitation violations.

Contributing: Letitia Stein, Mike Stucks and Cara Kelly