One of the patients, a 36-year-old woman, flew in from the United Arab Emirates and tested positive for the virus while undergoing quarantine at a hotel in Chek Lap Kok.
The centre said she carried the L452R mutant strain, though she had been double vaccinated with BioNTech jabs.
Another patient, a 21-year-old foreign domestic helper, tested positive for the virus while in quarantine at a hotel in Yau Ma Tei.
Both of them were asymptomatic.
There were fewer than five preliminary positive cases.