I believe HK is blocking entry for anyone outside of HK, China, Macau or Taiwan. If you are entering HK from anywhere, including the previously listed places, and you are a resident or citizen, you are required to quarantine for 14 days.
if you don't want to click the link here are the announcements I am referring to:
Hong Kong: The Hong Kong government announced that effective for a 14-day period beginning at 12:00 am on March 25, all non-Hong Kong residents arriving by air from any location other than mainland China, Macau, and Taiwan will be denied entry. Non-Hong Kong residents arriving from mainland China, Macau, or Taiwan will be denied entry if they have been to any overseas countries and regions in the past 14 days. Hong Kong residents and non-Hong Kong residents arriving from mainland China, Macau, or Taiwan with no travel to any overseas countries and regions in the past 14 days will be subject to a 14-day compulsory quarantine. The Hong Kong International Airport will suspend all transit services.
Starting from February 8, 2020, the Department of Health (DH) will issue quarantine orders to all people entering Hong Kong from the Mainland, including Hong Kong residents, Mainland residents and visitors from other places. People concerned must stay at designated places (quarantine centre, home or other accommodation) for a 14-day compulsory quarantine. Apart from the exempted persons under the "Compulsory Quarantine of Certain Persons Arriving at Hong Kong Regulation", people who have been to the Mainland in the past 14 days upon arrival at Hong Kong are also covered. They should not have any symptoms and should have passed temperature checks upon entry. Those with symptoms will be referred to the DH for further handling. Arrivals holding a visa with validity of less than 14 days will be denied entry.