COVID-19 has hit 78 nations so far, among them the U.S., where 11 have died. California, which has more cases than any other state and recorded its first death Wednesday, has now declared a state of emergency. Authorities are holding a cruise ship with at least 21 cases offshore near San Francisco. But some passengers had left the ship after a previous voyage, including the state's first coronavirus fatality, and federal health authorities are anxiously tracking others down.
Are we learning about the disease? Much about it remains unknown, but the World Health Organization is urging affected countries to increase testing in order to better understand the virus.