They include a 51-year-old man arriving from Pakistan, as well as a man and woman who arrived from France.
All of them have been inoculated.
Meanwhile, health authorities are looking into a case involving a 17-year-old boy who flew from Hong Kong to the UK last week, and tested positive on Sunday.
As a precautionary measure, officials said the Tsuen Wan building where he stayed during the incubation period – Block 7 of Belvedere Garden – will be subject to a compulsory testing order.
There are also about five preliminary positive cases.
The city has recorded 12,217 coronavirus cases so far.