https://www.theguardian.com/technology/2020/apr/16/coronavirus-facebook-misinformation-warning

Users who have liked, shared or commented on posts with false claims will be directed to WHO’s ‘myth busters’ page

Facebook will begin showing notifications to users who have interacted with posts that contain “harmful” coronavirus misinformation, the company announced on Thursday, in an aggressive new move to address the spread of false information about Covid-19.