There is huge difference between "no evidence of human to human transmission" and "evidence of no human to human transmission". The former means, we don't know yet. You can blame them for not knowing. But admitting that was right. And when they knew, they told everyone. At least in this instance, they haven't lost any credibility. On the contrary, it shows integrity to admit your limits of knowledge.

They knew it all by Jan 23rd

I'm guessing based on the other reply that you corrected the date. But how does WHO repeating a statement from Chinese authorities (attributed in the tweet) have anything to do with the WHO's credibility?

Nothing. "The WHO has lost all credibility" is a line that was parroted in every troll comment in February and early March; I guess this one hasn't yet gotten the memo, or maybe it's a bystander that's bought into it.

It's amusing how some people are reacting on a one-month or even two-month delay. I still see people saying that there's a new disease being covered up in Wuhan, or that we need to shut down travel from China, as if they were in a coma from mid-January all the way to late March. The actual situation changes faster than people's narratives of it.

"Preliminary investigations conducted by the Chinese authorities have found no clear evidence of human-to-human transmission of the novel #coronavirus (2019-nCoV) identified in #Wuhan, #China," - WHO.

Sounds like these were preliminary results, which would have been well rectified by February. Wuhan was under quarantine Jan 23.

There is a substantial difference in being wrong a month or so after a new virus is discovered, and being wrong after a country has been shutdown for nearly a month.

EDIT: Updated for correct date Jan 23, not Jan 29, of Wuhan shutdown.

Wuhan was under quarantine on Jan 23rd.

Precisely. I don't understand why the WHO would put out such information with reckless disregard of current events.

Both the WHO and the CDC have (deservedly) lost trust with the public.

I don't see any evidence in media or conversations that anything of the sort is true. If anyone has looked inept in the eyes of the public its potentially the federal administration in the USA. But what blame does WHO shoulder?

WHO appears to have been fairly well in front of this pandemic as soon as the evidence began to support it. The White House was in full denial/hoax mode until the end of February.