Cruise ship outbreak helps pin down how deadly the new coronavirus is
Exactly how deadly COVID-19 is remains up in the air. Limited testing and undetected cases — people with no symptoms or ones so mild they don’t seek medical attention — make it hard to pin down how many are infected. And that number is crucial for calculating the ratio of people who may die from COVID-19. Enter the Diamond Princess cruise ship. Quarantined at sea off Japan after a passenger tested positive for SARS-CoV-2, the ship became a natural data lab where nearly everyone was tested and few cases of infection were missed. Infections and deaths onboard suggest that the disease’s true fatality ratio in China is about 0.5 percent, though that number may vary from place to place, researchers report March 9 in a paper posted at MedRxiv.org. That 0.5 percent is far less than the 3.4 percent of confirmed cases that end in death cited by the World Health Organization, but...