All residents living in 09 flats at Nga Kwai House at Kwai Chung Estate are to be sent to a quarantine camp.
The same move has also been ordered for residents of 08 flats on the 12-14th floors of On Kwai House at Kwai Fuk Court.
Nga Kwai House has recently seen nine infections, including at three 09 units, while of three cases at On Kwai House, two involve 08 flats.
“It is suspected that vertical transmissions of virus were involved in the two buildings after initial investigation,” a government statement said.
Dr Albert Au from the Centre for Health Protection said the virus could have spread to flats in Nga Kwai House which had their U-shaped pipes removed.