The Hospital Authority (HA) said the baby's condition deteriorated quickly after she was admitted to hospital at 4 a.m. on Saturday.
A chief manager of the authority, Dr Lau Ka-hin, said the girl suffered from fever and convulsions before she was taken to Tseung Kwan O Hospital.
She was intubated and transferred to the intensive care unit (ICU) at Queen Elizabeth Hospital, where she was immediately prescribed antivirals.
However, Lau said, her condition continued to worsen and she suffered a cardiac arrest hours later.
The baby died last night.
Lau said he believes the girl was infected by her family members, as her parents, grandmother and caregiver had done rapid novel coronavirus tests at home which showed they had the virus.
Her twin sister and eight-year-old brother are also infected.
Lau said the baby had been healthy in the past, adding that her case has been referred to the coroner's court.
A dozen other patients infected with COVID-19 have also died.
On the daily infection figure, Dr Albert Au Ka-wing of the Centre for Health Protection said he expects the number of cases to continue to rise as the level of community transmission of the virus remains very high.
– RTHK, MPD
