These dates are wrong. China confirmed that the virus could be transmitted from person to person on January 20th. Japan and Hong Kong had patients with the virus a week before that.
The article states It took until the end of January before the WHO declared the coronavirus outbreak needed to receive international attention.
Which appears correct. Per the date you mentioned of Jan 20th, heres an article referring to Chinas position on that day:
https://www.cnbc.com/2020/01/21/china-coronavirus-human-to-human-transmission-confirmed.html
The Chinese official investigating a pneumonia outbreak stemming from a new coronavirus said the disease can spread from person to person but can be halted with increased vigilance, as authorities on Tuesday confirmed a fourth death.
Zhong Nanshan said there was no danger of a repeat of the Severe Acute Respiratory Syndrome (SARS) epidemic that killed nearly 800 people globally during a 2002-2003 outbreak, which started in China, as long as precautions were taken.