The study said that the data, communicated by Takuya Yamagishi, National Institute of Infectious Diseases, could not be used to determine whether transmission occurred from contaminated surfaces.

However, CDC said a further study of fomite transmission of SARS-CoV-2 aboard cruise ships was justified.

The report findings further show that more than 800 cases of laboratory-confirmed COVID-19 cases occurred during outbreaks on three cruise ship voyages, involving Diamond Princess and Grand Princess cruise ships, as well as cases linked to several additional cruises reported across the United States.

Transmission occurred across multiple voyages from ship to ship by crew members affecting both crew members and passengers. A total of 10 deaths associated with these two cruise ships have been reported to date.

During February 3–March 13, in the United States, approximately 200 cases of COVID-19 were confirmed among returned cruise travelers from multiple ship voyages, including the Diamond Princess and Grand Princess, accounting for approximately 17% of total reported U.S. cases at the time. Cases linked with cruise travel have been reported to CDC in at least 15 states, according to the study.

To remind, during February 7–23, 2020, the largest cluster of COVID-19 cases outside mainland China occurred on the Diamond Princess cruise ship, which was quarantined in the port of Yokohama, Japan.

Among 3,711 Diamond Princess passengers and crew, 712 had positive test results for the virus. Of these, 331 were asymptomatic at the time of testing. Among 381 symptomatic patients, 37 required intensive care, and nine died.

Infections also occurred among three Japanese responders, including one nurse, one quarantine officer, and one administrative officer.

During February 11–21, 2020, the Grand Princess cruise ship sailed roundtrip from San Francisco, California, making four stops in Mexico. Most of the 1,111 crew and 68 passengers from the voyage remained on board for a second voyage that departed San Francisco on February 21, with a planned return on March 7.

On March 4, a clinician in California reported two patients with COVID-19 symptoms who had traveled on the initial voyage, one of whom had positive test results for SARS-CoV-2.  More than 20 additional cases of COVID-19 among persons who did not travel on voyage B were identified from Grand Princess voyage A, the majority in California, including one death.

On the following day, a response team was transported by helicopter to the ship to collect specimens from 45 passengers and crew with respiratory symptoms for testing; 21 including two passengers and 19 crew, had positive test results.

Following docking in Oakland, California, on March 8, passengers and crew were transferred to land-based sites for a 14-day quarantine period or isolation.

During land-based quarantine in the United States, all persons were offered testing. As of March 21, of 469 persons with available test results, 78 had positive test results.

Repatriation flights for foreign nationals were organized by several governments in coordination with U.S. federal and California state government agencies. Following the disinfection of the vessel, remaining foreign nationals will complete quarantine on board. The quarantine will be managed by the cruise company, with technical assistance provided by public health experts.

On February 21, five crew members from voyage A transferred to three other ships with a combined 13,317 passengers on board. No-sail orders were issued by CDC for these ships until medical logs were reviewed and the crew members tested negative for the virus.

In the latest turn of events, over 100 people from Princess Cruises’s operated Ruby Princess tested positive to the virus, based on the latest updates from the New South Wales Ministry of Health (NSW Health). One passenger, in her 70s, who had been infected with the virus died this morning.