The Centre for Health Protection’s Chuang Shuk-kwan said the bulk of cases were locally transmitted infections involving people who had attended large-scale gatherings.
One cluster, for example, involved 47 people.
Chuang added that a number of cases have been detected in elderly homes, resulting in over 100 senior citizens being taken into quarantine.
There were about 500 preliminary positive cases.
The Hospital Authority’s chief manager, Larry Lee, urged people not to be complacent, saying while some Omicron patients suffered no or mild symptoms, others – especially the unvaccinated – can get very sick.
He urged people who’ve not been vaccinated to get jabbed as soon as possible.
Separately, the Director of Health, Ronald Lam, said an arrangement to allow close contacts of infected patients to undergo home quarantine took effect on Tuesday.
He said 38 people had been ordered to undergo self-isolation at home as of noon, adding that they will be given all the necessary assistance.