It came from nowhere with little warning, an unwelcome visitor in the night, just before China's most important annual holiday when millions would return home for the Lunar New Year. Scientists believe the new coronavirus now named Covid-19 may have first emerged at a massive seafood market selling wild animals, among other things, in the central Chinese city of Wuhan, capital of Hubei province. From quiet beginnings that included the punishment of a group of doctors who tried to expose the threat, Covid-19 rapidly spread throughout Hubei province. It expressed itself in a range of forms, from modest symptoms to lethal pneumonia, and spread across the country and to the rest of the world. It created one of the biggest global health crises since Ebola and severe acute respiratory syndrome (SARS), prompting the World Health Organization (WHO) to declare only its fifth global health emergency in the last decade.