The source of the story are two intellegence officers who spoke to newsweek.
"The contents of the the CIA document, called 'U.N.-China: WHO Mindful But Not Beholden to China,' were confirmed to Newsweek by two U.S. intelligence officials."
>https://www.dailymail.co.uk/news/article-8313615/CIA-believes-China-pressured-publicly-downplay-risk-coronavirus-January.html
https://www.newsweek.com/exclusive-cia-believes-china-tried-stop-who-alarm-pandemic-1503565