Entry requirement to Hong Kong from the US
From Jan 8 - Feb 4, Hong Kong will suspend incoming flights from the United States (US) and seven other countries (Australia, Canada, France, India, Pakistan, the Philippines, and the United Kingdom). All passenger flights from these eight places will be prohibited from landing in Hong Kong. And at the same time, persons who have stayed in these places for more than two hours will be restricted from boarding passenger flights for Hong Kong, so as to stop persons from the relevant places from travelling to Hong Kong via transit.
Hong Kong has classified overseas places into three tiers: Group A (high risk), B (medium risk) and C (low risk). The US is currently classified under Group A (high risk) specified places with enhanced surveillance. Details of the boarding and health quarantine requirements applicable to inbound travelers can be found here.
From Jan 16 to Feb 15, Hong Kong International Airport will suspend passenger transfer/transit services for any persons who have stayed in Group A specified places, including the US, in the past 21 days. Details of the transit services suspension can be found here.