My original comment pertained to a general pattern of communication from public health agencies-- I believe you were the first to bring up that tweet.

But if you want to explore the topic, by 14 January 2020 the virus had been sequenced for over a week, and its status as a beta-coronavirus with substantial sequence similarity to SARS established. Even if the sentence "preliminary investigations conducted by the Chinese authorities have found no clear evidence of human-to-human transmission" was true, rather than merely asserted by Chinese authorities (as now seems more likely) it's just not a terribly pertinent thing to report if you're trying to be Gricean about it. It was one instance of a pattern of minimization from public health agencies that persisted even after it was clear that SARS-CoV-2 had global reach: https://lessonsfromthecrisis.substack.com/p/things-can-get-r...