Most of the cases – either confirmed or preliminary positive with the Covid-19 virus – were from Yat Kwai House and Ying Kwai House, which are both under a five-day lockdown.
At a press conference, Chan said the risks of outbreaks for other buildings are lower, but residents of four blocks still need to get tested repeatedly in the coming week.
The Centre for Health Protection in total reported 125 new local infections on Sunday – the highest daily figure in a year.
Dr Chuang Shuk-kwan from the centre said they involved 94 residents or visitors from Yat Kwai House, one from Nga Kwai House and nine from Ying Kwai House.
One of the patients had bought a hamster on January 7 from a Mong Kok pet shop linked to an outbreak of the Delta variant.
Four of the new cases are unlinked.
They include an 18-year-old student who studies in Delia Memorial School in Mei Foo, a six-year-old boy who lives in Tung Chung, an unemployed woman who lives in Tai Wai, as well as a lift maintenance worker who lives in Ma On Shan and is believed to be carrying the Delta variant.
Chuang says there are so far more a hundred preliminary positive cases.