On January 30, the World Health Organization declared the coronavirus outbreak a Global Public Health Emergency. The WHO emergency committee had convened twice  (on January 22 and January 23) and had declined to make such a declaration for the novel coronavirus.
After about a week, at its third meeting, the WHO has declared the outbreak a Public Health Emergency of International Concern (PHEIC).
A PHEIC is defined as “an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response”. This definition implies a situation that is:
serious, sudden, unusual or unexpected;
carries implications for public health beyond the affected State’s national border;
may require immediate international action.
WHO Timeline related to the Wuhan Coronavirus
Jan. 30 WHO declares the coronavirus outbreak a Global Public Health Emergency after holding its third Emergency Committee. It recommends that the interim name of the disease causing the current outbreak should be “2019-nCoV acute respiratory disease”
WHO admits an error in its previous risk assessment of the virus and states declares the risk to be "very high in China, high at the regional level and high at the global level." explaining that it has stated "incorrectly" in its previous reports on January 23, 24, and 25 that the global risk was "moderate".
WHO declares the outbreak an "emergency in China", but stops short of calling it a global health emergency.
Jan. 20 (Human to human transmission confirmed)
Jan. 15 - Jan 20 (The virus spreads to other countries, including Japan and the United States)
Jan. 13 (First case outside of China)
WHO: "The possibility of cases being identified in other countries was not unexpected, and reinforces why WHO calls for ongoing active monitoring and preparedness in other countries. [...] The patient's full exposure history is under investigation. She reported a history of visiting a local fresh market in Wuhan on a regular basis prior to the onset of illness on January 5, 2020; however, she did not report visiting the Hunan South China Seafood Market from where most of the cases were detected."
Jan. 12 (China shares the genetic sequence of the novel coronavirus for countries to use in developing specific diagnostic kits)
The WHO says that according to the preliminary epidemiological investigation, most cases worked at, or were handlers and frequent visitors to the seafood market and that "the government reports that there is no clear evidence that the virus passes easily from person to person."
Jan. 9 (First death: a 61-year-old man from Wuhan)
WHO: "according to Chinese authorities, the virus in question can cause severe illness in some patients and does not transmit readily between people."
January 7 (Novel virus identified and named 2019-nCoV)
The WHO finds that the new virus is a new strain of coronavirus. The source is still unknown, but most likely comes from animals.
December 31, 2019
The WHO says it had been alerted to a "cluster of cases of pneumonia of unknown cause" in Wuhan, China.