Almost half of the coronavirus-stricken people aboard the Diamond Princess cruise ship never showed symptoms before they were tested, according to the Centers for Disease Control and Prevention.
More than 700 passengers and crew members have been diagnosed with COVID-19 since the boat docked in Japan on Feb. 3 and was quarantined for 14 days in Yokohama. Of those, about 46.5%, or 331 people, were asymptomatic at the time of testing, the CDC announced.
Of the 381 symptomatic patients, 37 (9.7%) required intensive care and nine (1.3%) died.
The lack of visible symptoms likely allowed the virus to spread aboard the Diamond Princess as passengers failed to quarantine themselves and crew members were still expected to keep working.
Traces of coronavirus were still on surfaces on the ship up to 17 days after the cabins were cleared, the CDC said.
