I think the WHO really did tweet that, but despite the occasional mistake they are a reliable source of information compared to the fire hose of misinformation coming from the President. There is an effort to blame WHO, the Chinese and anyone other than Trump - who was receiving reports from the best intelligence agencies in the world warning him about the coming pandemic, and he was still trying to claim it was a democratic hoax and false news. Now that he is taking it seriously we're supposed to believe that he always knew it was a pandemic.