It's just simply not true that China covered up the existence of the virus for months.

On December 16, 2019, the first patient was admitted to a hospital. This is more or less China's first reasonable opportunity to understand that there was a new disease.

On December 31, 2019, there was an article about it in the South China Morning Post: https://www.scmp.com/news/china/politics/article/3044050/mys...

And on DW: https://www.dw.com/en/china-investigates-sars-like-virus-as-...

And in Reuters: https://www.reuters.com/article/us-china-health-pneumonia-id...

So 2 weeks from discovery to worldwide news.