Final answer:
The 'silent killer' that emerged in Wuhan, China, in winter 2019 was the novel coronavirus known as COVID-19. It led to a global pandemic, affecting public health, prompting vaccine development, and causing widespread socio-economic impacts.
Step-by-step explanation:
The 'silent killer' that emerged in the winter of 2019 in Wuhan, China, refers to the outbreak of the novel coronavirus, later named COVID-19. This virus was first identified in Wuhan and swiftly spread to surrounding areas, affecting numerous smaller villages and towns. COVID-19 rapidly escalated into a global pandemic, drastically changing the everyday lives of people worldwide and prompting international responses to contain and manage the virus. Significant aspects of this event include the response of public health systems, the development and distribution of vaccines, and the socio-economic impacts that have been experienced globally.